Answer:
Stillman should register as an investment adviser representative in state P.
Step-by-step explanation:
Investment adviser representatives (IARs) must necessarily register in the state that they work in. In this case, Rock, Feller, and Standard (RFS) must be registered in all the states where it has offices functioning, but Stillman only needs to register in the state where his office is. If Stillman worked half year in state P and the other half in state M, then he would need to register in both states. But since this is not the case, then registering in state P should be enough.