One who is not easily pleased by anything

Maiden
Mediaeval
Precarious
Fastidious

The answer is D. Fastidious.

A fastidious person is one who is very particular and demanding, especially about minor details. They may be difficult to please and may often find fault with things.

The other options are not correct because:

  • A maiden is a young unmarried woman.
  • Mediaeval is another word for medieval, which means relating to the Middle Ages.
  • Precarious is dangerous or risky.

I hope this helps!