问答题
Which of the following is true according to Paragraph 2?
A.Chronic diseases are complex genetic puzzles to scientists.
B.How exceptional longevity-related genes function is known.
C.Most centenarians have exceptional longevity-related genes.
D.The integration of genes and environmental factors is important.
A.Chronic
B.
B.How
C.
C.Most
D.
D.The
E.