One who believes in the power of fate:

Answer: Option A

The one word substitution is Fatalist.

Optimist: hopefulness and confidence about the future or the success of something.
Pessimist: a tendency to see the worst aspect of things or believe that the worst will happen.
Parsimonious: very unwilling to spend money or use resources.
Fatalist: the belief that all events are predetermined and therefore inevitable.