Unsupported, because the stimulus doesn’t give us evidence concerning average global temperature. Even if you think ice caps are evidence of global temperature, the stimulus would suggest global temperatures shrank over the first 20,000 years, because the ice caps were growing.

Unsupported, because we don’t know the rate of growth or shrinkage. Ice caps grew for 20k years, then shrank for 10k years. But they could have grown much more than they shrank. This would mean the ice caps were larger at the end of the period.

Unsupported, because we don’t have reason to think that the period began at the “onset” of an ice age. An ice age could have been in effect for much longer, and the 30k period just begins in the final 20k years of an ongoing ice age.

Strongly supported, because concentrations of heavy oxygen grew for 20k years, then decreased for 10k years. This is evidence the ice caps grew during the first 20k years, then shrank in the next 10k years.

Unsupported, because an ice age might have started at the beginning of the period and ended in 20k years. There’s no evidence that the 30k period began just as an existing ice age was ending.