The following sentence may have an error in effective writing. the sentence or part of the sentence is underlined. choose the best revision for the underlined part. if no revision is necessary, choose the first answer. when the museum authorities investigated they found several mysterious crates in the basement. question 3 options: when the museum authorities investigated they found several when the museum authorities investigated; they found several when the museum authorities investigated, they found several when, the museum authorities investigated they found several save

This sentence does have an error--a grammatical one.

When the museum authorities investigated they found several mysterious crates in the basement. 

read the sentence out loud. doesn't it feel like a run on? there isn't any pause within it, but it has a sequence of events: the authorities investigated, the authorities found several mysterious crates. you'll want to insert a comma between "investigated" and "they"

When the museum authorities investigated, they found several mysterious crates in the basement. 

read it out loud again. you have a natural pause that helps you better understand the events and you have a comma separating the two ideas.