Since this appears to be a homework question Ill 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.