The answer is B. crossing over during prophase I
Chords that contain tones a half-step or whole-step apart are called Tone Clusters. It is a chord made up of tones only a half step or whole step apart. It can be produced on a piano by striking a group of adjacent keys with the fist or forearm.
If they have different sources of obtaining their required nutrients, food and other materials needed for survival. I believe.
The right answer is D.
The two men (Darwin and Lyell) were very close for several decades, both personally and scientifically. Darwin had read Lyell's Principles of Geology (1830-1833) during his voyage aboard the Beagle (1831-1836), in which he had found an important source of inspiration for developing his theory of natural selection.