Explanation:

- In the sentence "We need to protest against this policy," the word protest means to express strong objection or disapproval.

- Option 1: Resist - To oppose or stand firm against something. This is a suitable synonym as it captures the idea of opposing or pushing back against the policy.

- Option 2: Assent - To agree or approve, especially after careful consideration. This is not a synonym for protest, as it conveys agreement, not opposition.

- Option 3: Validate - To confirm or affirm the truth or validity of something. This is unrelated to protesting as it indicates support rather than opposition.

- Option 4: Perk - A benefit or advantage. This doesn't relate to protesting as it refers to a positive aspect, not an action of opposition.