Chromosomes are A: DNA strands that become visible during cell division
B: the control centers of cells
C: the thick, fluid material surrounding the nucleus
D: the basic units of structure in living things

A

Explanation:

Each chromosome contains a single double-stranded piece of DNA along with the aforementioned packaging proteins. Chromatin condensation begins during prophase and chromosomes become visible. Chromosomes remain condensed throughout the various stages of mitosis

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answer; the above statement is (true);

the index of refraction of the second medium is higher. i just took the test trust me !