B) DENV-2 strains.

Vietnamese strains Asian 1 Asian 2 America Cosmopolitan
Asian 1 1.44-5.41
Asian 2 6.07-9.78 6.0-8.14
America 10.22-11.46 8.61-11.08 7.51-10.61
Cosmopolitan 8.0-11.43 6.16-10.58 7.05-11.27 9.48-12.38
Asian-America 7.57-9.27 7.6-8.39 7.13-8.77 7.37-10.63 6.15-10.4