<span>The forces that control the motion of everyday objects are: gravity,friction, applied forces
Gravity pushed every object down and prevent them from flying up into the sky. Friction provides forces to the opposite way of every movement. Applied forces determine the way objects are moving according to the intention of those who do it.</span>
The term free trade can be found for example in NAFTA: North American Free Trade Agreement: it's a trade without additional obstacles, which is thought to be beneficial for both parties.
So the correct answer is;
c. trade without tariffs, quotas or other restrictions.
So, because of NAFTA there are not tariffs between US and Mexico.
