Foolhardiness is the result of constant strains.

Answer: Option D

Exhaustion : a state of extreme physical or mental tiredness.
Obstinacy : the quality or condition of being obstinate; stubbornness.
Sickness : the state of being ill.
Foolishness : lack of good sense or judgement; stupidity.
Foolhardiness : recklessly or thoughtlessly bold; foolishly rash or venturesome.

Synonym of Foolhardiness is Foolishness