Option A is not right bcs we can implement a Queue and we will see how.
Option D is not feasible, as implementing a queue with one stack is a lot of work and cannot be done with a single operation.
Option B is tempting but think about it, suppose you have "1" in stack, now you push "2", so your queue is [1[2[... now you want to dequeue so you reverse the stack and pop 1 and then again reverse the stack, these are three operations, not two.
While Option C is right, see this - say you have "1", you still reverse the whole stack as mandatory procedure then push "2" then you reverse the whole stack again, so now you have [2[1... now you pop 1 in a single operation and that's a perfect queue. To insert another number, you again reverse it then push the number then again reverse it.
Three operations to insert, one to delete.
Option C is the right one.