Final answer:
The letter that involves the situation where one part of the patient's mole does not match the other half according to the ABCDE rule for early warning signs of melanoma is letter A - Asymmetry.
Step-by-step explanation:
The letter that involves the situation where one part of the patient's mole does not match the other half according to the ABCDE rule for early warning signs of melanoma is letter A - Asymmetry. In this case, the mole is not symmetrical, meaning one half does not match the other half.