Question

which of the following is not an element of darwins theory of evolution by natural selection?
○ crossing-over
○ natural selection
○ struggle for existence
○ variation

Explanation:

Darwin's theory of evolution by natural selection includes elements like natural selection (the mechanism), struggle for existence (competition for resources), and variation (differences among individuals). Crossing - over is a process in meiosis related to genetic recombination, not a part of Darwin's original theory of natural selection.

Answer:

A. Crossing - over