As the children wander through the cave, what is Tom's reason for shouting?
The questions below are based on the following selection.

In the following excerpt from Mark Twain's The Adventures of Tom Sawyer, Tom Sawyer and Becky Thatcher find themselves on an adventure in a dark cave.

They started through a corridor, and traversed it in silence a long way, glancing at each new opening, to see if there was anything familiar about the look of it; but they were all strange. Every time Tom made an examination, Becky would watch his face for an encouraging sign, and he would say cheerily:

"Oh, it's all right. This ain't the one, but we'll come to it right a'ay!" But he felt less and less hopeful with each failure, and presently began to turn off into diverging avenues at sheer random, in the desperate hope of finding the one that was wanted. He still said it was "all right," but there was such a "leaden dread at his heart, that the words had lost their ring, and sounded as if he had said, "All is lost!" . . . ."

Tom shouted. The call went echoing down the empty aisles, and died out in the distance in a faint sound that resembled a ripple of mocking laughter . . . The children stood still and listened; but there was no result.

a.
to show that he is not afraid
b.
to listen to the echo of his voice
c.
to get someone's attention, so that they might be saved
d.
to express his anger with Beck