Friends, i am stuck with one of a question.can some plz shed some light in solving this question.thanks for the help

Q.Air at T = +16° C and DP = +4° C is forced from sea level over a 10.000 ft mountain range and descends back to sea level on the other side. If the leeward condensation level is observed to be 8.000 ft, what will be the final temperature?

A)18°

**B)**22° C)20° D)24°

ANS IS B.