Multiple choice for correct answer 'boys' - how do we know it's not 'girls'? It would then be 'khatiya' or something for 'eat'?
For multiple females, verb takes ती ending. For multiple males or a mixed gender group, the verb takes ते ending. I found the lessons from learning-hindi very helpful. Such as this one on verbs: http://www.learning-hindi.com/post/938215810/lesson-28-the-present-tense
लड़के is the plural form of लड़का (boy).
"Girls" would have been लड़कियां.