What si the debug output of the following apex code? Decimal thevalue; system.debug(thevalue);

In the code below, which type does String inherit from? String s = 'Hello World';

Which two statements are true about using the @testSetup annotation in an Apex test class? (Choose two.)

A SSN__ccustom field exists on the Candidate__ccustom object. The field is used to store each candidate's social security number and is marked as Unique in the schema definition.
As part of a data enrichment process, Universal Containers has a CSV file that contains updated data for all candidates in the system. The file contains each Candidate's social security number as a data point. Universal Containers wants to upload this information into Salesforce, while ensuring all data rows are correctly mapped to a candidate in the system.
Which technique should the developer implement to streamline the data upload?

A developer is tasked to perform a security review of the ContactSearch Apex class that exists in the system. Whithin the class, the developer identifies the following method as a security threat:
List<Contact> performSearch(String lastName){ return Database.query('Select Id, FirstName, LastName FROM Contact WHERE LastName Like %'+lastName+'%); } What are two ways the developer can update the method to prevent a SOQL injection attack? Choose 2 answers