Verified answer

Without the air to hold some of the sun's heat, the earth at night__is________, too cold for us to live

I would only put in "is".

To be honest with you, why not simply omit the blank and rephrase the statement.

Without the air to hold some of the sun's heat, the temperature of the earth at night would be too cold for us to survive.

.

I would say A - freezing cold. Frozen cold doesn't sound right.

A. A uses a gerund phrase to describe a hypothetical situation. For B, I think you mean "frozen solid" or just "frozen" which would work just as well, but "frozen cold" is not grammatically correct.

a

would freeze

a, is the only answer

I agree with answerer 1...

Without the air to hold some of the sun's heat, the earth at night IS too cold for us to live.

If you must have one of the above answers then it would be:

A. Would be freezing cold.

The tense of B is completely incorrect. So is A, but not as much.