Which statement contains an ironic use of understatement?
a) the boys were so exhausted after the long flight that they slept for hours.
b) we watched the different floats of the parade pass by for what seemed like an eternity.
c) i studied so hard for the test, i almost memorized the information written on my note cards.
eliminate
d) the pilot called flying from one side of the atlantic to the other a simple task of "puddle jumping."

Answer:

The statement which contains an ironic use of understatement is: The pilot called flying from one side of the Atlantic to the other a simple task of "puddle jumping." So, the right answer over here is Option D.

Explanation:

When an author or a writer wants to make a situation seem less important or significant  than it truly is then he/she makes an understatement. This figure of speech offers an ironic  effect to a statement and results in saying something opposite than what is expected. In this  statement mentioned above, the Atlantic ocean is ironically described as a puddle but it  actually means that the Atlantic ocean is gigantic.

600 dollars if i'm not mistaken.