Final answer:
The psychological concept in the statement is social conformity, which is the act of changing behavior to align with group norms and is associated with a need for acceptance or belief that the group is informed.
Step-by-step explanation:
In the statement, "A wise man can always be found alone. A weak man can always be found in a crowd," the psychological concept that it reflects is c) Social conformity. Social conformity refers to the act of changing one's behavior to match the responses or actions of others, an effect of social influence. This statement suggests an association between independent thought and strength of character, as opposed to the idea that those who seek solace in the crowd may feel the need to conform to group norms or decisions.
Groupthink, which is related but distinct, is a phenomenon that occurs when the desire for harmony in a group leads to an irrational or dysfunctional decision-making outcome. It includes symptoms such as the illusion of invulnerability and moral correctness, self-censorship, and the suppression of dissenting opinions within the group to maintain a false sense of consensus.