Answer:
A. New Zealand farmers have access to larger areas of pastureland.
Explanation:
What would best explain the difference in costs?
Let's examine each proposed answer and see if it makes sense:
A. New Zealand farmers have access to larger areas of pastureland.
Yes, makes sense. It's true that NZ farmers have access to more pastureland than those in California, since the population density is less in NZ than in California, and its more humid. That has as consequence that they need to purchase less grain for their cows.
B. Milk in California is more concentrated than milk in New Zealand.
Nope, even if California is dryer, the milk doesn't come out as dry milk.
C. Cows in New Zealand are more efficient at producing milk.
They might be a more efficient species of cows.... but that wouldn't explain such a large gap in costs.
D. New Zealand farmers feed their cattle more expensive grain.
If it was true, their costs would be higher than those in California... it's the opposite.
