Figure A shows the variation curve of DNA quantity in the process of somatic cell division and sperm formation in an animal testis, and Figure B shows each cell in the process of cell division.

(1) C in Figure B is in the prophase of mitosis, corresponding to ①; D is in the prophase of the second meiosis, corresponding to ④. < P > (2) The DNA in A nucleus is half that of somatic cells; The DNA in B and C nuclei is twice as much as that in somatic cells. The DNA in D nucleus is the same as that in somatic cells. < P > (3) The number of chromosomes in A and D is half that in somatic cells, and the number of chromosomes in B and C is equal to that in somatic cells. < P > (4) Among the four cells shown in Figure B, B and C contain homologous chromosomes. < P > Therefore, the answer is: < P > (1) ⑤ 314; < P >.

(3)b and c?

(4)b and c? B, c and d?

So the answers are:

(1)①④

(2)d

(3)b and c

(4)b and C.