The answer is natural selection
Answer: D
They often occur spontaneously, because when energy is released during a chemical reaction it does not usually happen slowly.
B. Wind.
A abiotic factor is non-living, making a, c and d wrong.
Answer:
True. The heart contracts twice per heartbeat. One contraction is the ventricular and the other one is the artrial.
Answer:
S phase
Explanation:
S phase is the second phase of interphase (longest phase where cell grows and replicates it's DNA and does it function. It is broken up into smaller sub phases). S phase is the synthesis phase. During this phase chromosomes are replicated ( The DNA is copied).