Explanation:

- Prevent means to stop something from happening or arising.

- Option 1: Construct refers to building or forming something, often physically or conceptually. It isn't related to stopping an event.

- Option 2: Provoke means to stimulate or incite someone into action, often anger or annoyance. It is often the opposite of preventing.

- Option 3: Allow means to let something happen or to give permission. It is contrary to preventing.

- Option 4: Avert means to turn away or prevent something undesirable from happening.

Given these, option 4 is indeed the correct synonym for "prevent."