Option D is the correct answer to the question
"He exercised while I watch television." because the tenses of the verbs don't match--"exercised" is past tense and "watch" is present.
Answer:
While I was smoking my cigar, a fire engine came roaring around the corner.
Explanation:
In the third option it's showing the time when the fire engine came and that too in correct form of words.
<span>A. I believe the Hubble telescope's photographs will open new frontiers in science.</span>
