Answer:
Treatment A and treatment B are the controls.
Step-by-step explanation:
Treatment A and treatment B are the controls.
There is no nuclease treatment in treatment A. This gives no DNA fragments and the chromatin is unimpaired.
In treatment B, naked DNA is digested with a nuclease. Since micrococcal nuclease particularly cuts exposed or naked DNA, it cuts this naked DNA into several fragments with different lengths.
Both of these treatments are the controls. Treatment A tells us about the length of the chromatin fiber and what happens when no nuclease treatment is given, while treatment B tells us what happens to the exposed DNA once it is treated with micrococcal nuclease.