Antonym of ARTIFICIAL

Answer: Option D

Artificial : made or produced by human beings rather than occurring naturally, especially as a copy of something natural.
Solid : firm and stable in shape; not liquid or fluid.
Truthful : telling or expressing the truth; honest.
Authentic : of undisputed origin and not a copy; genuine.
Natural : existing in or derived from nature; not made or caused by humankind.

Antonym of Artificial is Natural