What is also called "swimmer's ear"
a. otitis media
b. otitis exterma
c. otitis interna
d. none of these options are correct

B. otitis exterma  

Explanation:

Every ear infection is called otitis. It will be called otitis externa (also known as a "swimmer's ear") if it affects the skin-lined outer ear region consisting of the ear pinna and the outer ear canal that ends in a membrane called the eardrum.

The most common cause of this type of earache is bacterial and fungal infection. Most of the time, these microorganisms penetrate through damage to the outer ear's skin caused by objects (swabs, staples, for example), scratching or drying of the ear, and contact with contaminated water (sea, pool, baths). Frequent contact with water can make it easier to remove the wax that protects the ear canal.

one centimetre is equal to 0.01 metres