How can we specrfy the type of Security (basic auth, oauth) used by the API in OpenAPI Specification 2.0?

How can we specrfy the type of Security (basic auth, oauth) used by the API in OpenAPI Specification 2.0?
A . specify using the secuntyDefinrtions name property
B . specify using the secuntySchemas name property
C . specify using the security Variables name properly
D . specify using the securityParams name property

Answer: C