The correct answer is: A. Increasing the web thickness.
Web crippling is a type of failure that can occur in beams when the web of the beam is subjected to excessive bearing stress. This can happen when the beam is loaded in a way that causes the load to be concentrated on a small area of the web. The web can then buckle and fail.
One way to avoid web crippling is to increase the thickness of the web. This will make the web stronger and less likely to buckle. Another way to avoid web crippling is to provide suitable stiffeners. Stiffeners are plates or bars that are attached to the web of the beam. They help to distribute the load more evenly and prevent the web from buckling.
Increasing the length of the bearing plates will not help to avoid web crippling. In fact, it may make the problem worse. This is because the longer the bearing plates, the more concentrated the load will be on the web. This can increase the risk of web buckling.
Therefore, the correct answer is A. Increasing the web thickness.