Answer: A) I felt bad after sitting in front of the computer all day (does that happen to you?) so I went for a bike ride.
Step-by-step explanation: when writing a text or a sentence, we should pay attention to the rules of capitalization to use them correctly. In the given sentence, the phrase in parentheses is a question about sitting in front of the computer all day, as it is a question, it should include a question mark at the end (and inside the parentheses), also it is the continuation of the sentence, so it shouldn't be capitalized, so the correct answer is option A.