Here are the DNA sequences from 2 different regions of the genome of an organism.
Region 1: 3’ – ATTAGAATGGTTAGCCAATATATA – 5’
Region 2: 3’ – GGCTGCCAGCGCAGGGCTTAGG – 5’
Which of these would require a higher temperature to melt & why?

Since this appears to be a homework question I’ll just give you a couple of hints.
First, Region 1 is longer
Second, Region 2 has a much higher G+C content

Which has the higher Tm? Try googling oligo & tm. You will find quite a few Tm calculators which will answer this question

The answer to why depends how sophisticated of an answer you need. The question could be asked in high school or college. For a reasonably sophisticated answer see "DNA denaturation" as Wikipedia.

Region 2 has require a higher temperature to melt because it consist of much higher G and C content which have strong bonds between them and which therefore require a higher temperature to break