Which three lines in this excerpt from elizabeth bishop's "the fish" show that the fish has given up struggling for survival after living a hard life?

right angles are formed by perpendicular lines. if the lines would extend, to make two intersecting lines, they would form four right angles.

mark twain, real name samuel langhorne clemens, was an american writer, humorist, entrepreneur, publisher, and lecturer. among his novels are the adventures of tom sawyer and its sequel, the adventures of huckleberry finn, the latter often called "the great american novel". wikipedia

i think that the answer is substandard.