This looks very similar to a problem I solved, where I wanted something like "Hamburgers, Pizza, Steak" in the detailed admin notification email template.
I created an ExpressionManager function called "listifop", that I would like to submit to be included in em_core_helper.php

The function definition is:
'listifop' => array('exprmgr_listifop', 'LEMlistifop', gT('Return a list of retAttr from sgqa1...sgqaN which pass the criteria (cmpAttr op value)'), 'string listifop(cmpAttr, op, value, retAttr, glue, sgqa1, sgqa2,...,sgqaN)', '', -6),

For example for the above food multiple choice selections you would have: listifop( 'value', '==', 'Y', 'question', ',', that.food.sgqa )

Just to clarify the idea behind the suggested new function "listifop" is that it will basically behave like the countifop function but it's return value will be like that of the implode function.
So it'll be like countifop + implode => listifop

So if there are no objections I'd like to submit a pull request for this with the following code which I have already been using in my survey:

function exprmgr_listifop( $args )
{
$result = "";
$cmpAttr = array_shift($args);
$op = array_shift($args);
$value = array_shift($args);
$retAttr = array_shift($args);
$glue = array_shift($args);

$validAttributes = "/" . ExpressionManager::$RDP_regex_var_attr . "/";
if ( ! preg_match( $validAttributes, $cmpAttr ) ) return $cmpAttr . " not recognized ?!";
if ( ! preg_match( $validAttributes, $retAttr ) ) return $retAttr . " not recognized ?!";

foreach ($args as $sgqa)
{
    $cmpVal = LimeExpressionManager::GetVarAttribute($sgqa,$cmpAttr,null,-1,-1);
    $match = false;

    switch ($op)
    {
        case '==': case 'eq': $match = ($cmpVal == $value); break;
        case '>=': case 'ge': $match = ($cmpVal >= $value); break;
        case '>' : case 'gt': $match = ($cmpVal > $value);  break;
        case '<=': case 'le': $match = ($cmpVal <= $value); break;
        case '<' : case 'lt': $match = ($cmpVal < $value);  break;
        case '!=': case 'ne': $match = ($cmpVal != $value); break;
        case 'RX': try { $match = preg_match( $value, $cmpVal ); }
        catch ( Exception $ex ) { return "Invalid RegEx"; } break;
    }

    if ( $match )
    {
        $retVal = LimeExpressionManager::GetVarAttribute($sgqa,$retAttr,null,-1,-1);
        if ( $result != "" ) $result .= $glue;
        $result .= $retVal;
    }
}

return $result;

}

Where displaying result ?

In export : do your own export
In print answers : can be done in theme

Displaying result in email.

Submitted PR #1215, please review

PR#1215 was accepted, and released in 3.16.1
This issue can now be closed as resolved.