Answer:
Sister chromatids. (Ans. B)
Explanation:
Sister chromatids are defined as the identical chromatids formed by the DNA replication of the chromosome, both copies of chromatids are joint together by a centromere. A pair of chromatids are known as dyad.
A set of sister chromatids formed during the S phase or synthesis phase of interphase, while all the chromosomes present in a cell is replicated. During the process of mitosis, or second division of meiosis the two sister chromatids are gets separated from each other into two different daughter cells, and each cell receives one copy of the chromosomes.
A membrane bound nucleus (or just a nucleus in general)
<em><u>Answer</u></em>
<em><u>about 3.9 billion years ago</u></em>
<em><u>about 3.9 billion years agoThe most recent common ancestor of all currently living organisms is the last universal ancestor, which lived about 3.9 billion years ago.</u></em>
