Read the following passage and circle the letter A, B, C or D to indicate the correct answer to each of the questions.

The tooth decay

In most animals, dental decay is a rare problem. In man, and especially in the rich West, the disease has reached epidemic proportions.

The cause of tooth decay in human beings is a bacterium that feeds on the sugar in our food. It digests the sugar more easily by converting it into an acid. The acid then dissolves the enamel, the outer coating of the teeth and finally attacks the living nerve within. The result is the agonizing pain we know as toothache.
 

The last sentence means that toothache is a condition which is often ____________.

A. unbearable                                                  B. quite unexpected
C. a bit unpleasant                                                      D. unpleasant but bearable