Riddle

Forward I am heavy, but backward I am not.

Choose an answer

A.A Truck
B.Gravity
C.Iron
D.A ton
Hint: It's a 2-word phrase with 4 letters, starting with "A".

Answer

A ton

Why this is the answer

'Ton' is a unit of heavy weight; spelled backward it is 'not.'

This riddle is filed under Riddles for Adults and rated Medium.