Eng Question!!Help!!

I think it should be the first one--they are dirty because the question is ''wash your (hands)'',{not hand} , so ''it is'' is not correct
For the third one, if you are dirty, i think the question should be '' go and have a bath, tom''

3.You are dirty .

They are dirty.

'they' means 'Tom's hands'. As 'Tom hands' are plural, we can't use 'it'. If you choose the third answer, it means 'Tom is dirty'

1.They are dirty