Which statement is true?

a. If one party is more productive in producing both products, it has a comparative advantage in producing both goods
b. None of the listed statements are true
c. A party can have a comparative disadvantage in producing both goods
d. A party has the comparative advantage in producing a good if it has the absolute advantage in producing the other good
e. If parties specialise and trade, it is only the less productive party that can experience any gains from trade