When controlled for social class and educational opportunities, Lambert and his colleagues found that bilingual children performed on intelligence tests.

A). Better.

Explanation:

As per the question, the test conducted by Lambert along with his colleagues revealed that the 'bilingual children performed better on intelligence tests' as they possess enhanced cognitive capabilities. A bilingual individual possesses an improved inhibitory control that allows him/her to switch quickly as their control mechanisms are also more active in comparison to the mono-lingual. Thus, the bilinguals would have an edge over the monolingual in social class as well as educational opportunities as they have improved memory, elevated relative control, and heightened cognitive capabilities. Thus, option A is the correct answer.