Answer: Whats the question exactly?
Explanation:
what is being underlined?
The best revision of this sentence is the following:
The lawyer presented a clear argument to the jury (it was unbelievable how influenced they were by his case) in the hopes of winning the trial.
A pair of parentheses needs to be used in order to separate this information from the rest of the sentence and facilitate reading and comprehension. The information in the parentheses is related to the meaning of the sentence but in some way it interrupts the flow, so a pair of parentheses is necessary in order to indicate this.
