Suicide is killing yourself on purpose, dying at your own hand, that is, taking your own life. For example, "the depressed woman committed suicide". Hence, Option A is correct. Among the rest of the options, slaughter means to kill an animal for food, homicide means murder, immolation means to kill yourself or someone else, or to destroy something, usually by burning, in a formal ceremony. These options do not express the intended meaning, hence incorrect.