The correct answer is TRUE (the statement is absolute).
The statement "all monkeys have tails" is ABSOLUTE because it is referring to the 100% of the monkeys as having tails. Such a claim does not leave the door open to any other possibility. The use of "all" is absolute.
For example, in the sentence "all women support the abortion" we have an absolute and not true affirmation because we know that not all the women think the same.