Answer: Option B
Explanation: A gene is the specific portion or sequence on the DNA (Deoxyribonucleic acid) that is able code for a functional protein. Thus, the entire DNA sequence in each cell consists of several genes and some non-coding portions that all makes up the complete hereditary information usually called genome.
Observe this linear chain
Cell -> Chromosomes -> DNA -> Gene.
The above illustrates that a gene is the basic carrier of hereditary information.
This will definitely help.