Answer:
C. Mark has a comparative advantage in writing TV commercials and Krystal has a comparative advantage in writing poems.
Explanation:
Mark has absolute advantage in both as it can outproduce Krystal in both, ppoems and TB commercials
now, referring to comparative advantage:
Mark opportunity cost for TV comm: 12/4 = 3
Krystal opportunity cost for TV comm: 8/2 = 4
It has comparative advantage doing TV comm as it renounce to less poems
Mark opportunity cost for poems: 4/12 = 1/3
Krystal opportunity cost for poems: 2/8 = 1/4
Krystal has a comparative advantajge as it renounce to a quarter of TB commercial per poem while Mark to a third