Rank the following melting temperature of the DNA fragments (assuming they interact with their perfect complement) from lowest (1) to highest (4):
5' - ATATGCGATTTCTTA- 3'
5' - ATATAAAATTTCTTA- 3'

a) 2, 1
b) 1, 2
c) 1, 2, 3, 4
d) 4, 3, 2, 1