A mesh collider: O a. Is faster than a box collider O b. Is as accurate as the triangle count on the mesh O c. Is the only way to get headshots to work O d. Is the only viable option for complex meshes such as player characters In an Al system that uses planning, when performing an action we start by: O a. Clearing the action list O b. Adding the action to be performed to the action list O c. Scanning all pre-conditions for the desired result O d. Scanning all post-conditions for the desired result