If __ are present then lubrication must be performed. a. Steering knuckles b. Ball joints c. Stabilizer bar bushings d. Grease fittings

## Step 1<br />The problem is asking us to identify which component in a vehicle requires lubrication. The options provided are steering knuckles, ball joints, stabilizer bar bushings, and grease fittings.<br /><br />## Step 2<br />Steering knuckles, ball joints, and stabilizer bar bushings are all parts of a vehicle's suspension system. These parts are typically lubricated to reduce friction and wear.<br /><br />## Step 3<br />Grease fittings, on the other hand, are not a part of the vehicle's suspension system. They are a type of fitting that allows for the introduction of lubrication into a system. They are not a component that requires lubrication themselves.