Application properties can be defined in .yaml or in .properties file.
MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/configuring-properties#supported_files

Entire event would be sent to each route in parallel.
Scatter-Gather works as follows :
- The Scatter-Gather component receives a Mule event and sends a reference of this Mule event to each processing route.
- Each of the processing routes starts executing in parallel. After all processors inside a route finish processing, the route returns a Mule event, which can be either the same Mule event without modifications or a new Mule event created by the processors in the route as a result of the modifications applied.
- After all processing routes have finished execution, the Scatter-Gather component creates a new Mule event that combines all resulting Mule events from each route, and then passes the new Mule event to the next component in the flow.

Logs would look like:
INFO 2021-06-09 19:14:56,039 [[MuleRuntime].uber.06: [validationtest].batch-job-validationtestBatch_Job-work-manager @6de10f3e] [processor: validationtestFlow/processors/1/route/0/route/0/aggregator/processors/0; event: bfb751e1-9939-11eb-9f69-02053763653a] org.mule.runtime.core.internal.processor.LoggerMessageProcessor:
[
"\"A\"",
"\"C\"",
"\"D\""
]
--
INFO 2021-06-09 19:15:02,486 [[MuleRuntime].uber.06: [validationtest].batch-job-validationtestBatch_Job-work-manager @6de10f3e] [processor: validationtestFlow/processors/1/route/0/route/0/aggregator/processors/0; event: bfb751e1-9939-11eb-9f69-02053763653a] org.mule.runtime.core.internal.processor.LoggerMessageProcessor: [
"\"E\""
]
Batch aggregator value is 3. Hence in first time it will print ["A", "C", "D"] and in next iteration it will print [ "E" ]
-------------------------------------------------------------------------------------------------------------------------------------------------- Correct answer is [ "E" ]

Correct answer is
%dw 2.0
output application/json
import modules::Utility
---
Utility::encryptString( "John Smith" )
DataWeave 2.0 functions are packaged in modules. Before you begin, note that DataWeave 2.0 is for Mule 4 apps. For Mule 3 apps, refer to DataWeave Operators in the Mule 3.9 documentation. For other Mule versions, you can use the version selector for the Mule Runtime table of contents.
Functions in the Core (dw::Core) module are imported automatically into your DataWeave scripts. To use other modules, you need to import the module or functions you want to use by adding the import directive to the head of your DataWeave script, for example:
import dw::core::Strings
import camelize, capitalize from dw::core::Strings
import * from dw::core::Strings
The way you import a module impacts the way you need to call its functions from a DataWeave script. If the directive does not list specific functions to import or use * from to import all functions from a function module, you need to specify the module when you call the function from your script. For example, this import directive does not identify any functions to import from the String module, so it calls the pluralize function like this: Strings::pluralize("box").
Transform
%dw 2.0
import dw::core::Strings
output application/json
---
{ 'plural': Strings::pluralize("box") }