You need to define a secret in the release pipeline. The secret can only be used in the “Release” stage of the pipeline. 
Where would you define the secret in the pipeline?

Answer options:

A.In the variables section
B.In the secrets section
C.In the options section
D.In the pipeline section

Answer A 
You would define this in the “Variables section”. 
This is given in the Microsoft documentation. 

Since this is clearly given in the Microsoft documentation, all other options are incorrect. 
For more information on variables in Azure pipelines, please visit the following URL- 

https://docs.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops