"Relinquish" means to give up or let go of something, while "Possess" means to own or have something.

"Calm" and "excite" are opposites, with calm representing a state of tranquility or lack of agitation, while excite indicates an increase in energy or agitation.

"Upgrade" involves improving or raising to a higher level, so the opposite or antonym would be "Demote," which involves lowering or reducing to a lower level. Therefore, option (C) Demote is the most suitable antonym in this context.

"Flabby" describes something that is soft, loose, or lacking firmness. Therefore, "Firm" is the opposite, indicating solidity or a lack of flabbiness.

"Shallow" refers to something having little depth, while "deep" represents the opposite, indicating a significant depth.

"Exodus" refers to a mass departure or exit of people, often used to describe a large group leaving a place. The antonym, "Homecoming," signifies a return or arrival back to one's home or place of origin. Therefore, "Homecoming" is the opposite of "Exodus" as it involves people coming back home rather than leaving.

"Moil" means to work hard or toil, so the opposite or antonym would be "Discourage," which implies dissuading from effort or work. Therefore, option (C) Discourage is the most suitable antonym in this context.