The disorder is Emphysema.
It is a type of chronic obstructive pulmonary disease that presents as an abnormal and permanent enlargement of air spaces distal to the terminal bronchioles. It frequently occurs in association with obstructive problems and chronic bronchitis.
Answer:
12
Explanation:
Suppose the four different strains are P, Q, R, S. Thus, the first infection can be from any of the four strains and it occurs in 4 ways.
Since an individual cannot be infected again with the strain from which he/she is been previously infected;
Then, at the second time;
The possible number of strain to be infected with = 4-1 = 3 ways
Thus; the number of possible different levels of severity can be viewed by forming two lettered word P, Q, R, and S without repetition which is:
= 4 × 3
= 12
Change through natural selection
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