Please Refer to the Following Information to Answer the Next

Multiple Choice

Please refer to the following information to answer the next few questions.
Diploid nuclei of the ascomycete, Neurospora crassa, contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores.
-Each of the eight ascospores present at the end of mitosis has the same chromosome number and DNA content (ng) as each of the four cells at the end of meiosis. What must have occurred in each spore between the round of meiosis and the round of mitosis?

A) double fertilization
B) crossing over
C) nondisjunction
D) autopolyploidy
E) S phase