Recent research shows that greenhouse gas levels are higher today than they have been at any point in the past _____ years.

A) 25
B) 150
C) 500
D) 800 000

Greenhouse Gas

Gases in Earth's atmosphere that trap heat, contributing to the greenhouse effect and global warming, including carbon dioxide and methane.

Past Years

Refers to the previous periods or times before the present, often recalled for historical events, experiences, or changes over time.