Seven boxes A, B, C, D, E, F and G are kept in a stack from bottom to top but not necessarily in the same order. Box D is kept above box E but below box F. Box G is kept at one of even numbered position but not at the top position. Box B is kept immediate below Box G. Box A is kept immediate above Box C, which is neither kept at the bottom nor at a prime numbered position. Box D is kept at a prime numbered position. Which of the following box is kept at the topmost position?