Processes are generally swapped out from memory to Disk (secondary memory) when they are suspended. So. Processes are not swapped during context switching.
TLB : Whenever any page table entry is referred for the first time it is temporarily saved in TLB. Every element of this memory has a tag. And whenever anything is searched it is compared against TLB and we can get that entry/data with less memory access.
And Invalidation of TLB means resetting TLB which is necessary because a TLB entry may belong to any page table of any process thus resetting ensures that the entry corresponds to the process that we are searching for.
Hence, option (C) is correct.