Answer:
answer is d) all of these choices are correct.
Inheritance is the process by which traits are passed from the parents to their offspring. The basic unit of inheritance in human is the DNA. For traits to be passed from the parent to the offspring, the DNA in the cell must be duplicated and this happens through the process of cellular reproduction.
The answer should be proteins. Because the protein is consists of different kinds of amino acids(usually 20 in total). And our cell can not produce essential amino acids itself.
