Final answer:
DNA sequences with a high proportion of base-pairs between Adenine (A) and Thymine (T), as well as between Cytosine (C) and Guanine (G), are the most stable.
Step-by-step explanation:
Adenine (A) and Thymine (T) are complementary base pairs in DNA and they form two hydrogen bonds between them, making them stable. Similarly, Cytosine (C) and Guanine (G) are also complementary base pairs and they form three hydrogen bonds between them, which increases their stability.