According to Piaget's Cognitive Development Theory, 'The basic unit of the…

CONCEPT: In Jean Piaget's Cognitive Development Theory, a schema (plural: schemata) is the basic unit of cognitive organisation — a mental structure that organises related knowledge and experience. Schemas are built and revised through two complementary processes: assimilation, which fits new information into an existing schema, and accommodation, which modifies an existing schema (or creates a new one) when new information does not fit. Together these processes let schemas guide how a person interprets and responds to the world, i.e. they implement cognitive behaviour.

APPLICATION: The question asks for the basic unit of cognitive structure that helps implement cognitive behaviour — this is exactly what Piaget calls a schema, the elementary organisational unit into which experience and knowledge are structured.

CROSS-CHECK: This is confirmed by contrasting each of the other terms with a schema:

• Reflexes are innate, involuntary sensorimotor reactions present from birth (e.g. sucking, grasping) — the biological starting point of infant behaviour, not an organised, revisable cognitive structure.

• Basic Instincts names an innate biological drive, not a term used in Piaget's framework for cognitive organisation; instincts are not built or modified through assimilation and accommodation.

• Conservation is the later-developing understanding that a quantity stays the same despite a change in its arrangement or appearance — a cognitive ability/milestone that emerges once schemas have matured, not the basic unit of structure itself.

RESULT: Hence, among the options offered, only schema names the basic unit of cognitive organisation described in the question.