13. In eukaryotic cells, DNA is found principally in the nucleus, but it also occurs in _ and in _ .
(A) ribosomes； mitochondria,
(B) mitochondria； chloroplasts,
(C) chloroplasts； peroxisomes,
(D) peroxisomes； vacuoles,
(E) vacuoles； mitochondria.

1. 題目解析題目問的是在真核細胞中，...