For I to be cfl one more condition need to be satisfied along with m+p=n+q that is m>=n
Reference:
https://www.cs.utexas.edu/~cline/ear/automata/CS341-Fall-2004-Packet/3-SupplementaryMaterials/D-SuppContextFree.pdf
check page no 10 of pdf
for option IV as multiplication symbol is not given there we can consider it as concatenation
lets take example
a^30 b^5 c^200 d^105
now here m=30 n=5 p=200 q=105
mn=p+q is 305=305
now we can design pda as following
1)push 10 'a' for Each input 'a' in stack
2)push all b's in stack
now stack contains 305 a's and b's for above example
3)match all a and b in stack with input c and d
4)if stack is empty and input is null then accept otherwise reject