How to Group data with same id in a join query

Hello, please i have this in my controller
$pollModel = new Poll();
$polls = $pollModel->join('options', 'options.poll_id = polls.poll_id')->findAll();
if i loop through this it works but the problem is i have an option with same poll_id that  is more than one.. so it loop them differently instead of making them one..
i also tried to use groupBy()
$polls = $pollModel->join('options', 'options.poll_id = polls.poll_id')->groupBy('options.poll_id').findAll();
this is close to the answer but it only return just one option like if i have three option with same poll_id it only returns the first one..
Any help??