Final answer:
O6-methylguanine, a type of DNA damage, is repaired by methyl guanine methyl transferase (MGMT) through a process of direct reversal, where the damage is chemically reversed without the need for a template.
Step-by-step explanation:
The repair of O6-methylguanine, a type of DNA damage, is done through a process called methyl guanine methyl transferase (MGMT). This process is a method of direct reversal, where the damage is chemically reversed without the need for a template. MGMT removes the methyl group from the guanine base, restoring it to its original form.