Jira Automation on approver field

[Sharadkumar Bangera]

Hello,

I am working in Jira and i would like to have script for below task

1) The "Approval" field only to be active when the option is "A" and option is "B" and for rest option the approver filed to be HIDDEN

2) while creating a ticket , when i select option A, the  approvers name automatically appears lets say "ABC" and "XYZ" and when i selct B  the approvers to be changed and name appears automatically "DDD" and "FFF" 

Can you plz provide the script and where should i write this script in behaviour