Darryl Can Build Picnic Tables Twice as Fast as Trevon

Multiple Choice

Darryl can build picnic tables twice as fast as Trevon. Darryl can assemble swing sets three times as fast as Trevon. The law of comparative advantage suggests that

A) Darryl can gain only at Trevon's expense.
B) Trevon can gain only at Darryl's expense.
C) both can gain if Darryl specializes in assembling swing sets and Trevon in building picnic tables.
D) both can gain if Darryl specializes in building picnic tables and Trevon in assembling swing sets.