Final answer:
The term referring to all mental activities such as thinking, knowing, remembering, and communicating is 'cognition', which encompasses a range of complex processes studied by cognitive psychology.
Step-by-step explanation:
The term that refers to all the mental activities associated with thinking, knowing, remembering, and communicating is cognition. This includes various complex processes like perception, problem-solving, judgment, language, and memory. Cognitive psychology is a field that is dedicated to studying these aspects of how people think and internalize the world around them.
Options like algorithms and heuristics pertain to specific problem-solving strategies; an algorithm is a step-by-step procedure for solving a problem, while a heuristic is a more general problem-solving framework that acts as a mental shortcut. However, when we talk about the broad range of mental activities, cognition is the most encompassing term.