The phrase "for a joke" at the end of the fourth stanza serves to ) create some humor in the passage.b) relieve the tension by created humor.c) demonstrate the power of man over nature.d) show that nature can be harsh and unfeeling.

The correct answer is option D) show that nature can be harsh and unfeeling.

Explanation:

At the end of the fourth stanza of the poem Sea Lullaby written by Elinor Wylie, the phrase "for a joke" refers to the fact that nature has no regrets for that murdered child. As if it were a joke for her. "She choked him and beat him to death, for a joke."

The sea, in all its greatness dragged him and hit him with its waves.

Another form of insensitivity is when the author says "Now in silence she lingers, Beside him all night, To wash her long fingers, In silvery light.”.

true, true, i have to agree