An experimenter lines up pairs of checkers into two identical rows. Then the experimenter elongates one of the rows by spacing the checkers farther apart. This is a classic test of:
A. conservation of volume.
B. conservation of area.
C. conservation of number.
D. conservation of matter.

ANSWER: (c) CONSERVATION OF NUMBER

EXPLANATION: Psychologically, Conservation refers to the ability of an individual to understand that despite the change in the appearance of an entity, the quantity remain the same.

According to Piaget's theory of cognitive development, children develops the abilities of conservation (in terms of number, area, volume, and orientation), and this stage occurs between age seven to eleven.

Thus, the experimenter is testing conservation of number, which is characterised by the ability to understand that when redistributing two entities (two identical rows), its number is still the same and not affected.

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