Assertion- The bands of polytene chromosomes become enlarge at certain regions to form puffs or balbiani rings.
Reason- These enlarged bands are active genes and represent the site of RNA synthesis.
A. Both assertion and Reason are true and reason is the correct explanation of assertion
B. Both assertion and reason are true, but reason is not the correct explanation of assertion
C. Assertion is true, but reason is false
D. Assertion is false, but reason is true