Select the option that can be used as a one-word substitute for the given group of words.
That which cannot be satisfied

* Insatiable means impossible to satisfy (e.g., an insatiable appetite).
Stubborn means having or showing dogged determination not to change one's attitude or position on something.

Drastic means likely to have a strong or far-reaching effect; radical and extreme.

Prickly means covered with prickles; or ready to take offense.