Which of the Following Are the Two Conditions Required to Be

Which of the following are the two conditions required to be present in order for the police to seize an item in plain view without a search warrant?

A) A crime must have been committed and the officer must have reason to believe the evidence will be found in a given location.
B) A crime must have been committed and there must be exigent circumstances.
C) The officer must be legally situated, and he must have probable cause to believe the item is evidence of illegal activity.
D) The officer must have probable cause to believe the item is evidence of illegal activity and he must knock and announce his presence before obtaining entrance through force.