Trailhead code critiques

Notes on Bulk Triggers Unit

//alternative or additional query to show sub query that is not unbounded

    for(Account a : [SELECT Id,Name 
                     FROM Account 
                     WHERE Id IN :Trigger.New 
                     	AND Id NOT IN (SELECT AccountId 
                                       FROM Opportunity
                                       WHERE AccountId in : Trigger.New)]){
    	System.debug(a);
    }