!@#$%^&*()

a> lower.

reason:- the amnt of heat incident will be same.
amnt of heat radiated by earth's surface is also same.
only diff is that this heat gets trapped in the atmosphere and makes us feel warmer.but without atmosphere, this heat will get easily radiated and thus make the avg temp lower.

[correct me if wrong.]

it would be lower becoz heat would not be held....
instead it will be radiated continuosly and rapidly to space.[1][1]