A common error in academic writing is the tendency to

The correct answer is C. Write overly formal sentences that use big words for the sake of sounding "academic"

Explanation:

Academic writing refers to a style of type of writing used in the formal, official or academical documents this style includes the use of reliable evidence, the use of technical or scientific terms and applying all norms in terms of style and writing. Also, in academical writing, the use of the first and second person or pronouns "I" and "you" should be avoided due to objectivity as well as the use of informal words such as slangs or dialects, except in direct quotes.

Additionally, due to the features of this type of writing, it is common writers want to use excessively technical, scientific or sophisticated words to sound "academic" along with complex and long sentences, which is a common mistake as these type of words should be only used when they are required and sentences should remain simple to be clear for readers. Therefore, one common mistake in academic writing is the tendency to write overly formal sentences that use big words for the sake of sounding "academic".