What must you do before signaling when overtaking a vehicle?

Before signaling when overtaking a vehicle, it is imperative to check safety first. This means ensuring that it is safe to change lanes and that there is sufficient space to overtake the vehicle ahead. Checking for oncoming traffic, the presence of other road users, and any potential obstacles in your path is crucial to prevent accidents.

Taking the time to assess these factors ensures that your maneuver is safe and legal. Once you have confirmed it's safe, you can then proceed to signal your intention to overtake, indicating to other drivers what you plan to do. This sequence of checking for safety and signaling helps maintain safety on the road for all users.

The other options do not adequately address the safety precautions necessary for overtaking. For example, signaling immediately does not take into account whether it is actually safe to make the maneuver, and accelerating to pass without ensuring safety could lead to dangerous situations. Looking for a gap is important, but it is a part of the broader safety check that needs to occur beforehand.