Option 1: Honest -> This is a synonym of candid, meaning truthful and sincere, not an opposite.
Option 2: Forthright -> This is also a synonym of candid, meaning direct and straightforward in speech.
Option 3: Selfless -> This relates to being unselfish and concerned with others' needs, unrelated to the meaning of candid.
Option 4: Secretive -> This means keeping things hidden or concealed, which is directly opposite to being open and frank.
Hence, Option 4: Secretive -> Candid means being open, honest, and straightforward, while secretive means withholding information and being reserved or hidden in one's communication -> correct