Answer:
Mr. Bixby asks, "Didn't you know there was no bottom in that crossing?"
Explanation:
The short story "A Cub Pilot" is an autobiographical narration about the author Mark Twain's experience during his time working as a cub pilot on a steamboat on the Mississippi River. This story reveals how he gets to learn more about confidence and the need for security for the pilots, in whose hands the lives of all those on board depends.
One instance shows Twain being made to pilot the boat while the captain Mr. Bixby went below. When asked if he could manage it, Twain confidently assured that he can even cross the river<em> "with [his] eyes closed".</em> But when Mr.Bixby questioned him how much water is in the river, he boldly declared he couldn't hit the bottom of the river<em> "with a church steeple."</em> Soon after, he began to falter in his confidence, making mistakes after mistakes which, in the end, Mr. Bixby told him<em> "there was no bottom in [that] crossing"</em>. Mr. Bixby's rather simple yet objective question suggests that if one has enough confidence and belief in oneself, then there is nothing that can shake our belief or be afraid.
Thus, the <u>correct answer is the fourth option</u>.