What is the distinction between disease and infection?

What is the distinction between disease and infection?
 
  a. An infection means that bacteria or viruses are present in the body; a disease means that a person is experiencing symptoms associated with an infectious organism, or other pathological mechanism.
  b. A disease means that bacteria or viruses are present in the body; an infection means that a person is experiencing symptoms associated with an infectious organism, or other pathological mechanism.
  c. A disease is when symptoms are present for less than a month; an infection is when symptoms are present for more than a month.
  d. An infection is when symptoms are present for less than a month; a disease is when symptoms are present for more than a month.