Question

1. why are individuals in many developing countries susceptible to diseases such as polio and pertussis?

because of a lack of education
because of a lack of vaccination
because of poor hygiene
because of genetic variation

Explanation:

Polio and pertussis are vaccine - preventable diseases. In many developing countries, there may be limited access to vaccines due to various factors such as cost, logistical challenges in vaccine distribution, and lack of awareness about vaccination programs. A lack of education (while it can play a role in overall health - seeking behavior) is not the most direct cause for susceptibility to these specific diseases. Poor hygiene is more related to diseases like diarrhea - causing infections rather than polio and pertussis. Genetic variation is not a major factor in the susceptibility to these two infectious diseases which are preventable by vaccination.

Answer:

because of a lack of vaccination