Read the paragraph.

Other ships might have come to the rescue of the Titanic if not for communication errors. For some reason, the Titanic did not immediately receive help from other ships. For example, the Californian could have come to the assistance of the sinking vessel. Some reports suggest that the Californian’s radio operator was not on duty to hear the distress signals.

Which of the following is the paragraph’s topic sentence?


Other ships might have come to the rescue of the Titanic if not for communication errors.
For example, the Californian could have come to the assistance of the sinking vessel.
Some reports suggest that the Californian’s radio operator was not on duty to hear the distress signals.
For some reason, the Titanic did not immediately receive help from other ships.