1. My parents … in the garden for 3 hours. А) works В) are working С) has been working D) have been working

My parents gave been working in the garden for 3 hours.Have my parents been working in the garden for 3 hours?Have my parents been working in the garden for 3 or for 5 hours?How long have my parents been working in the garden?Where have my parents been working for 3 hours?Who has been working in the garden for 3 hours?My parents have been working in the garden for 3 hours, haven\'t they?