Fit as a fiddle

Do you know the English phrase “fit as a fiddle“? Read the conversation below. Can you guess the meaning?

Ben: Hi Karen, how’s your father doing? I haven’t seen him since he had an operation on his back.

Karen: It took a few months for him to get over the operation, but he’s fit as a fiddle now. He’s even thinking about running a marathon next year!

Does it mean:

a) a good fiddle player

b) a good runner

c) fit and sporty

d) in good health

The answer is below! ↓

Answer: d) in good health