var active_correct_answer;

function toggle_correct_answer(el_id) {
	var el = document.getElementById(el_id);
	
	var show = true;
	if ( window.active_correct_answer != undefined ) {
		window.active_correct_answer.style.display = 'none';
	
		if ( window.active_correct_answer.id == el.id ) {
			show = false;
			window.active_correct_answer = undefined;
		}
	
	} 	
	
	if ( show ) {	
		el.style.display = 'inline';		
		window.active_correct_answer = el;
	}
}