Final answer:
The language in the given sentence, which includes vocabulary such as 'efficacy' and 'discredited', best describes intellectual language due to its use of precise and knowledge-based terms. Option A is the correct answer.
Step-by-step explanation:
The sentence "The study proved the efficacy of the product and discredited its disparagers" best fits the description of intellectual language. Intellectual language pertains to the cognitive use of words that claims knowledge which can be verified as true or false.
The use of terms in this sentence such as 'efficacy' and 'discredited' aligns with conveying logical, semantic, systemic, and empirical information—attributes of intellectual language. These words also relate to areas like intelligence quotient (IQ) and natural concepts, which underline the precise and knowledgeable aspect of the language used.
Furthermore, this language contributes to the ways humans create and agree upon norms within their cultures, exemplified by the roles of 'efficacy' and 'disparagers' in shaping perspectives about the product.