Final answer:
B) Samurai and knight armor shared the common characteristic of providing good protection, which was integral to their combat effectiveness.
Step-by-step explanation:
An important similarity between samurai and knight armor is that B) Both samurai and knight armor provided good protection.
While the samurai armor was primarily made from materials like leather and metal designed to be both protective and more flexible to allow freedom of movement, knight armor included chain armor and greaves, with the ultimate goal of physical protection during battle.
Both types of armor were simultaneously functional and decorative, reflecting the status and skill of the wearer.