1. Which of the following statements most accurately describes spark plug heat range? A. The length of the threaded portion of the shell usually denotes the spark plug heat range. B. A hot plug is designed so that the insulator tip is reasonably short to hasten the rate of heat transfer from the tip through the spark plug shell to the cylinder head. C. A cold plug is designed so that the insulator tip is reasonably short to hasten the rate of heat transfer from the tip through the spark plug shell to the cylinder head.