In English many nouns can be turned into verbs without any change to their form. For instance, the noun walk can be turned into the verb to walk. This phenomenon is known as ______ in morphology.

A．the earliest group of Puritans immigrating to America
B．the patriots who drafted the Declaration of Independence
C．the group of brave explorers who discovered America
D．the earliest radical British Catholic church reformers

A．Heartfelt.
B．Windmill.
C．Brainwash.
D．Nationalize.