In the process of evolution by natural selection illustrated in this figure, what is the mechanism or agent of natural selection? 
Definitions:
Heuristic
A simple, efficient rule or method used to make decisions, learn something, or solve problems quickly.
Door-In-The-Face Tactic
Multiple-request technique to gain compliance, in which the focal request is preceded by a larger request that is bound to be refused.
Compliance Technique
Strategies used to persuade or influence others to agree with or obey a request or command.
Emotional Tactic
A strategy that uses emotions to influence or manipulate others' decisions or perceptions.
Q3: Some fish have bony fins. If the
Q8: What accounts for the similarity between seaweeds
Q24: Evolutionary evidence suggests fungi evolved from _
Q29: _ are the most diverse group of
Q32: Scientists hypothesize that disrupting our _ communities
Q36: As an experiment, you infect bacteria with
Q46: "Sticky ends" are _ that are produced
Q58: RNA vaccines have shown promise but have
Q69: To be classified as having rapid ejaculation,
Q88: Antidepressants are often used to treat obsessive-compulsive