Insert the appropriate preposition in the following sentence out of the given options:
You must dispense ______ his services.

Dispense with (Phrasal Verb)
English Meaning: to get rid of or do without something:
Example Sentence:
- Let’s dispense with the formalities and get right down to business.
The speaker is asking the listener to get rid of his services.
The verb 'Dispense' forms no phrasal verb with any other prepositions given in the options.
The complete sentence is: You must dispense with his services.

Source: Cambridge Dictionary