Which Piece of Evidence Is the LEAST Convincing for the Critical-Period

Multiple Choice

Which piece of evidence is the LEAST convincing for the critical-period hypothesis?

A) Abdelleh's language ability never fully developed.
B) Different neural mechanisms are used to process a second language by individuals who learned a second language in infancy and those who learned a second language after puberty.
C) The most proficient English speakers among immigrants to the United States are those who began learning English before age 7 years.
D) Adults are more likely than children to experience permanent language impairment as a result of brain damage.