What is the first rule of a safe and legal turn?

Answer: D — Move into the proper lane early

When making a turn, it is important to move into the proper lane early to ensure the safety of yourself and others on the road. This allows you to have better visibility and control of your vehicle while turning and can help prevent accidents. Option A, signaling well in advance, is also important as it alerts other drivers of your intentions. Option B, checking side mirrors only, is incorrect as it neglects to mention the importance of checking rearview mirrors as well. Option C, looking over your shoulder, is also incorrect as it should be done in addition to checking mirrors, not instead of. Therefore, option D, moving into the proper lane early, is the most essential first rule of a safe and legal turn.