Select the option that can be used as a one-word substitute for the given group of words.

Treat with a vaccine, usually by injection to promote immunity against a disease

Inoculate

The word that can be used as a one-word substitute for "treat with a vaccine, usually by injection to promote immunity against a disease" is inoculate.

• Innuendo is a hint or suggestion, especially one that is indirect or discreet.
• Inoculate means to introduce a vaccine into the body to prevent a disease.
• Innumerate means unable to count or estimate numbers.
• Innovate means to introduce something new or to make changes in something established.

Inoculate is the most appropriate word for the given group of words because it specifically refers to the act of introducing a vaccine into the body. It is derived from the Latin word inoculare, meaning "to graft."