There are 3 options: 1) Two sites, "mobile" and "desktop", both responsive; 2) One site, responsive; 3) Desktop site and mobile site. Option 1 is the bes

There are 3 options: 1) Two sites, "mobile" and "desktop", both responsive; 2) One site, responsive; 3) Desktop site and mobile site. Option 1 is the best and most expensive to implement, 3 is worst and almost same expensive. So "optimal" is 2, when best is 1.