'Learning' is a mental activity. This comes under which of the following:

Concept: Theories of learning explain HOW human beings acquire knowledge and skills, and each anchors its explanation in a different central mechanism -- an observable change in behaviour (behaviourism), an internal mental/cognitive process (cognitivism), active construction of knowledge from experience (constructivism), or connections formed across a network (connectivism).

Application: The stem states that learning is a MENTAL activity -- an internal process of the mind involving perception, memory, thinking, reasoning, and problem-solving. This is precisely the defining claim of the Cognitive theory of learning (associated with theorists such as Piaget, Bruner, and the Gestalt psychologists), which frames learning as internal information processing rather than as an externally observable behaviour change.

Cross-check -- why the other theories do not fit:

• Behavioural theory defines learning as an observable change in behaviour from stimulus-response and reinforcement, deliberately setting aside internal mental states -- the opposite emphasis of 'mental activity'.

• Constructive theory centers on learners actively constructing their own knowledge through experience and interaction; its defining feature is the act of construction, not a general claim that learning is a mental activity.

• Connective theory (connectivism) explains learning as forming and navigating networks of connections among people, information, and technology, emphasising networks rather than internal mental processing.

Result: Since the statement 'learning is a mental activity' is the defining premise of cognitivism, it comes under the Cognitive theory of learning.