I don't think creating a cookie in javascript will help you out in this scenario. What i understand is you need to get one of the three options which the users has selected more. Once the user is selected one of the object you nees to store the value selected by the user in the database or some where in the form of XML along with the user id and finally you can generate a report or fetch the max number of users who selected which object etc....
anyways Here is how to set a cookie in javascript:
function SetCookie(cookieName,cookieValue,nDays) {
var today = new Date();
var expire = new Date();
if (nDays==null || nDays==0) nDays=1;
expire.setTime(today.getTime() + 3600000*24*nDays);
document.cookie = cookieName+"="+escape(cookieValue)
+ ";expires="+expire.toGMTString();
}
Thanks