Respuesta :
Answer:
Option A. He explained the principle of internal-combustion (although not very well)
Explanation:
Option A is missing a period at the end of the sentence.
Periods are used at the end of any sentence that is intended to make a statement. The period should be placed directly behind the last letter of the last word of the sentence.
In this case, after finishing a sentence with parenthesis, a period should be set after the parenthesis, not after the last word inside it.
"... (although not very well)."