Select the option that can be used as a one-word substitute for the given group of words.

A secret agreement especially in order to do something dishonest or deceive people

Collusion

The correct one-word substitute for a secret agreement especially in order to do something dishonest or deceive people is collusion.

• Collision refers to a violent impact between two or more moving objects.
• Collocation refers to the occurrence of two or more words together in a phrase or sentence.
• Colloquy refers to a conversation or discussion between two or more people.
• Collusion refers to a secret agreement or cooperation, especially between two or more parties, for a fraudulent or dishonest purpose.

Collusion is the most appropriate word for this group of words because it specifically refers to a secret agreement that is made for the purpose of deceiving or defrauding someone. The other words do not have the same connotation of dishonesty.