The correct answer is (D) realize.
After "made me," the causative structure requires a bare infinitive (base verb without "to"), so "realize" is correct.
The verb "make" is a causative verb. In the structure make + object + bare infinitive, the base form of the verb is used without "to" (e.g., made me realize, not made me to realize). Options A (realizing) and C (realized) are grammatically incorrect here, and B (to realize) incorrectly adds "to."