which is best CoS Category for PSW visa holder

Hello I am Creating a new CoS for somebody who is currently on "Graduate Leave to Remain" visa (also known as PSW visa I think). He was a student and finished Masters Degree and currently on Graduate Leave to Remain visa. He studied into the same filed where I am offering him a job.

Now my question is: I am creating a new CoS for above employee, and the SMS shows the following options on the very fist page:

In the Select the Category, the SMS shows the following options:

a) Skilled Worker (Switching Immigration Category - ISC liable)
b) Skilled Worker (Extensions - ISC exempt)
c) Skilled Worker (Extensions - ISC liable)
d) Skilled Worker (Change of Employment - ISC exempt)
e) Skilled Worker (Change of Employment - liable)
f) Skilled Worker (Graduate in Tier 4/Student Route Switching to Skilled Worker)
g) Skilled Worker (Switching Immigration Category - ISC exempt)

Can you please advise me which option should I choose?
Thanks for your help guys!

Hello,
Can someone please reply?

Sounds like f), but I personally had no experience with that.

Hello all,
Can someone else also comment please who feels more confident?
Thanks

Why are you not contacting the Business Helpdesk that you have access to at UKVI to ask these questions? Or review the Sponsorship guidance notes.