Of outstanding significance

A. Meaningful

B. Ominous

C. Evident

D. Monumental

E. Rational

Answer: Option D

Solution(By Examveda Team)

One word substitute is Monumental.

Meaningful: having meaning.
Ominous: giving the worrying impression that something bad is going to happen; threateningly inauspicious.
Evident: clearly seen or understood; obvious.
Monumental: great in importance, extent, or size.
Rational: based on or in accordance with reason or logic.