Explanation:

Both A and R are true and R is the correct explanation of A
The Mediterranean lands are also known as the world’s orchard lands.
A wide range of citrus fruits such as oranges, lemons, limes, citrons and grapefruit are grown.
The fruit trees have long roots to draw water from considerable depths during the long summer drought.
The thick, leathery skin of the citrus fruits prevents excessive transpiration.
The long, sunny summer enables the fruits to be ripened and harvested.
The Mediterranean lands account for 70 per cent of the world’s exports of citrus fruits.