All of the following might lead to a disease caused by an opportunistic pathogen except

An encounter with an affected animal

Explanation:

Note:

hormonal changes, changes in diet and immune suppression might lead to a disease caused by an opportunistic pathogen.

Bonus:

An opportunistic pathogen can be bacteria, viruses, fungi, or protozoa that take advantage of an rare opportunity to infect it's due to weakened immune system, a disruption in the host gut microbiota/integumentary barriers.

An opportunistic pathogen can not cause disease Where there is normal immune system in the host

the answer to you question is   jet streams

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.