Option C is right ..
ROM is super slow in front of the processor, therefore if it was interfaced, the performance of the system will decrease, so in this sense, it is difficult to interface with CPU
RAM or main memory is DRAM only, and it is interfaced with CPU as we all know using a memory module which takes care of refreshing and decoding stuffs,etc and the cache is SRAM and directly interfaced with the CPU chips
I suppose it is option C
The question is ambiguous and vague, it should have clearly defined what is meant by interfacing, directly or indirectly