Final answer:
Gardasil 9 vaccine covers the most strains of HPV compared to the other options.
Step-by-step explanation:
The HPV vaccine that covers the most strains is Gardasil 9. Gardasil 9 vaccinates against the four types included in Gardasil (types 6, 11, 16, and 18) and an additional five high-risk types (31, 33, 45, 52, and 58). Cervarix vaccine includes only HPV types 16 and 18. Therefore, Gardasil 9 provides the widest coverage against different strains of HPV.