(A) Ignition is achieved by the heat of compression created by compressing intake/charge air within the cylinder into a relatively small volume.
(B) Ignition is achieved by intense heat by passing an electric current through the element of a specially designed glow plug.
(C) Ignition is achieved by the heat of compression created by compressing the air/fuel mixture within the cylinder into a relatively small volume.
(D) Ignition is achieved by a high voltage electric spark induced across the gap of a specially designed spark plug.

If choice A is selected set the score to 1.