Dogs are inbred for such desirable characteristics as color; but an unfortunate by-product of such inbreeding can be the emergence of characteristics...

Dogs are inbred for such desirable characteristics as color; but an unfortunate by-product of such inbreeding can be the emergence of characteristics such as deafness. A 1992 study of bull terriers (by Strain and others, as reported in The Veterinary Journal) found the following:

(i)50% of the studied bull terriers are white.

(ii)11% of the studied bull terriers are deaf.

(iii)20%

of the white bull terriers are deaf.

What is the probability that a randomly chosen bull terrier is white and deaf?

 a. .11 / .50 = .22

 b. .20 / .50 = .4

 c. .11 / .20 = .55

 d. .50 * .11 = .055

 e. .50 * .20 = .1

 f. .11 * .20 = .022