Which of the following best describes sti symptoms?
a.
symptoms for stis are similar in nature and severity.
b.
symptoms may not be present even though there is an infection.
c.
visible symptoms are limited to the genital area.
d.
symptoms can be treated with over-the-counter medication

The answer is letter b. symptoms may not be present even though there is an infection. Sexually Transmitted Infection/s or STI's have different variations, some of which when you acquire do not show any signs of infection or symptoms, until it is already in a severe stage. So it would be better if you have a regular check-up or regular tests to see if you are indeed infected with STI.

"air pollution" is the correct answer i believe