The UiPath Remote Runtime component is a component that enables the communication between a remote application or desktop, such as Citrix Virtual Apps, and the dedicated UiPath extension, such as the UiPath Extension for Citrix or the UiPath Extension for Windows Remote Desktop. It gathers information about the targeted UI elements of the remote applications and sends them to the corresponding extension, so that selectors can be natively generated in UIExplorer1. This way, you can create and manage tasks and exchanges between users and external applications using the authentication process of the API provider2. The UiPath Remote Runtime component is required to establish the connection between an application or desktop server and a corresponding UiPath extension installed on a client machine, without having to rely on OCR and image recognition activities3.
References:
* Studio - About UiPath Remote Runtime - UiPath Documentation Portal.
* Integration Service - Connections - UiPath Documentation Portal.
* UiPath UiPath Runtime - Citrix Ready Marketplace.

The error "Object reference not set to an instance of an object" occurs because dtReports has not been initialized before use.
To fix this, the correct approach is to initialize the DataTable before adding rows, using:
dtReports = New System.Data.DataTable
Explanation of Each Option:
* A (Assign dtReports = New System.Data.DataTable) # (Correct Answer)
* Initializes a new empty DataTable, which is required before adding rows.
* Once initialized, dtReports can hold columns and rows.
* B (Assign New System.Data.DataTable = dtReports) # (Incorrect)
* Incorrect syntax. New System.Data.DataTable must be assigned to a variable, not the other way around.
* C (Assign dtReports = New System.Data.DataRow) # (Incorrect)
* DataRow represents a single row, not the entire DataTable.
* We need to initialize the table first, not just a row.
* D (Assign dtReports = New List(Of DataRow)) # (Incorrect)
* A List(Of DataRow) is not a DataTable. UiPath's Add Data Row activity only works with DataTable, not with lists.
References:
* UiPath Official Docs - Add Data Row
* UiPath Forum - Object Reference Error

To convert a string variable "InvoiceTotal" to a numeric format that includes decimals, the expression Double.
Parse(InvoiceTotal) should be used. This method converts the string representation of a number in a specified style and culture-specific format to its double-precision floating-point number equivalent.
References:
* Microsoft .NET Documentation: Double.Parse Method

UI Automation is a feature that enables you to automate the interaction with UI elements on remote machines using native selectors. To use UI Automation in a scenario where multiple RDP connections are involved, you need to install the UiPath Windows Remote Desktop extension on the client machines and the UiPath Remote Runtime component on the destination machine. The extension allows you to identify UI elements on the remote desktop and send keyboard and mouse events to them. The Remote Runtime component enables the communication between the extension and the UiPath Robot service. In this case, Machine A and Machine B are client machines, while Machine C is the destination machine. Therefore, you need to install the RDP extension on Machine A and Machine B, and the Remote Runtime component on Machine C. (UiPath Studio documentation1) References:
* 1: About Native RDP Automation - UiPath Studio.

Variables and arguments are both used to store and pass data in UiPath, but they have some differences in their scope and direction. Variables are used to pass data between activities within the same workflow file.
They have a default direction of In/Out, which means they can be read and written by any activity in the workflow. Arguments are used to pass data between different workflow files. They have a specific direction of In, Out, or In/Out, which means they can only be read or written by the workflow that invokes them or the workflow that is invoked. Variables and arguments can have different data types, such as String, Int32, Boolean, etc. Variables can be assigned to an argument value, but arguments cannot be assigned to a variable value. References: Managing Arguments, Variables, Arguments, and Control Flow in Studio, Different between variables and arguments