Select the correct answer from the list.(2 points)

In the greenhouse effect, far infrared radiation is(absorbed by, emitted and absorbed by, emitted) Earth's surface and absorbed and reemitted by (some, all) gases in the atmosphere. These gases have (decreased, been unchanged, increased) in concentration over the past century.

In the greenhouse effect, far infrared radiation is emitted and absorbed by Earth's surface and absorbed and reemitted by all gases in the atmosphere. These gases have increased in concentration over the past century.