function checkAnswer(which) {
	var elem = which;
	while (elem.nodeName && elem.nodeName.toLowerCase() != "li") {
		elem = elem.parentNode;
	}
	var divs = elem.parentNode.getElementsByTagName("div");
	for (var i=0; i < divs.length; i++) {
		if (divs[i].className == "answer-explanation") {
			divs[i].style.display = (divs[i].parentNode==elem ? (divs[i].style.display=="block" ? "none" : "block") : "none");
		}
	}
}