H4 transfer I539 filing Question???

H4 transfer with H1 from one Univ to another, need to file I-539
Part 2 application Type,
I am applying for:
a.An extension of stay in my current status.
b.A change of status. The new status I am requesting is:
c. Other: (Describe grounds of eligibility.)-------

Which one should I chose? How long it takes now?
Urgent!
Thank you ver much!