Given, Process size =32 MB = 2^25 B
PTE= 4 B = 2^2 B.
For minimizing total overload due to page table and internal fragmentation
Page size >= Page table size.
Let page size be p
We know that, Page table size= no. Of pages * PTE
So, p >= (2^25)/p * 2^2 B
p^2 >= 2^27 B
p >= 2^(27/2) B
So, p min will be 2^14 B = 16 KB