Assertion: Environmental deprivation has been found to lower intelligence.

Reasoning: Rich nutrition, good family background, and quality schooling have been associated with increased intelligence.

Both the assertion and reasoning are true, and the reasoning is the correct explanation of the assertion.

Children from disadvantaged homes adopted into families with higher socioeconomic status exhibit a large increase in their intelligence scores. There is evidence that environmental deprivation lowers intelligence while rich nutrition, good family background, and quality schooling increases intelligence.