A. unfaltering
B. irresolute
C. unwavering
D. lazy
Strenuous : requiring or using great effort or exertion.
Unfaltering : steady; resolute.
Irresolute : showing or feeling hesitancy; uncertain.
Unwavering : not wavering; steady or resolute.
Lazy : unwilling to work or use energy.
Antonym of Strenuous is Lazy
