Livestock is very expensive because THE LIVESTOCK ARE INEFFICIENT IN CONVERTING PLANT FOOD INTO MEAT. The correct option is A.
Fruits and vegetables, which are lower on the food chain grow much more quickly and are available almost all through the year, this makes them easy to obtain and cheap. On the other hand, food from animal source such as meat, egg, milk, etc are much more expensive because it takes time for the livestock to grow and be ready to eat compare to fruit and vegetables.