Answer:
A gene is a section of a double-stranded molecule known as DNA. This molecule is found within the nucleus of the cell, contained in threadlike structures called chromatin. The two strands form a double helix linked by a series of paired bases. The base adenine is always linked to thymine and the base cytosine is always linked to guanine.
One of the challenges that scientists face when classifying a new fossil is that any tiny detail is all that separates one species from another. Further exploration is required to identify another set of characteristics that may help in deciding which organism belongs or create a new class.
The correct answer is C) only some survive because variation exists