You are most likely talking about the radar, which scans and alerts the people on the submarine of other submarines, missiles, etc. nearby.
Answer:
I think it would be lighthearted
Explanation:
None of the other answers really make sense, but if you are allowed a second answer if it is not lighthearted it would probably be serious
The answer is D
I just did the question
The following sentence is punctuated correctly. Well, I said my prayers; however, he simply turned and limped off.
Answer: True