Which of the following diseases is caused by a virus?
a. african sleeping sickness
b. common cold
c. tuberculosis
d. athlete’s foot

The correct answer would be B. common cold.

Common cold refers to the viral infection of the upper respiratory tract.  

Numerous virus can cause common cold such as rhinovirus (the most common cause), human coronavirus, influenza viruses, adenoviruses, human respiratory syncytial virus et cetera.

The sign and symptoms may include running nose, coughing, sore throat, headache, sneezing, and fever.

The treatment may include the use of antibiotics and antivirals and therapies like hydration, gargling, and rest, which help in relieving the symptoms.

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion

the answer to your question is sperm