Answer:
d. both countries, as whole, will be better off.
Step-by-step explanation:
When countries leverage on their comparative advantages, they will be better off. In this instance as US has comparative advantage in producing airplanes, it will be more cost effective for them to produce and export to Japan.
So also Japan will find it cheaper to produce televisions and export to the US. Both contries reduce cost by producing goods they have comparative advantage in.