The correct option is C Cistron
Cistron is the segment of DNA involved in the transcription that having information for the synthesis of a particular RNA or protein.
A sense strand, is the segment within double-stranded DNA that carries the translatable code in the 5′ to 3′ direction, and i.e. complementary to the antisense strand of DNA, or template strand, which does not carry the translatable code in the 5′ to 3′ direction.
Recon is the smallest unit of DNA capable of undergoing crossing over and recombination. Muton is the smallest unit of DNA that can undergo mutation.
So, the correct answer is "option B"