Answer:
The correct answer is - genes.
Explanation:
Mendel was the first to understand the heredity and inheritance that some specific factors are responsible for the inheritance which are present in the pairs and separated during gamete formation and each gamete one copy from it.
These factors are actually the genes that are the basic unit of the heredity and are the sequence of the nucleotide that encodes for the specific protein production.
Thus, the correct answer is - genes.