Which sentence uses a colon correctly?

after buying groceries, we unloaded: the canned food, fresh vegetables, milk, and ice cream.

reed sent his application for camp to: soccer for all, 20 market street, denver, co.

projects may be dropped off at the following locations: room 16, room 78, or room 3.

patrick received letters of congratulations from: aunt julie, grandma, and his friend william.

C) Projects may be dropped off at the following locations: Room 16, Room 78, or Room 3.

Explanation: A colon is a punctuation mark usually used to introduce a list of elements or an explanation. A colon should never separate a verb from its object (like its happenning in option A, separating the verb "unloaded" from its objects "the canned food" "vegetables", etc), it also shouldn't be used to separate a preposition from its object (like in option B and D, separating "to" and "from" from their objects). So the correct answer is option C, where the colon is introducing a list of elements.

caliban is prospero's slave in the shakespear's play "the tempest"