Why are individuals in many developing countries susceptible to diseases such as polio and pertussis?

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

because of lack of vaccination

Explanation:

this occur mostly in Nigeria

The first blank can be correctly filled up with proteins.

Proteins are complex molecules which play many crucial roles in the body such as structural role (actin, myosin, keratin), movement, metabolism (enzymes), signal transduction, transport, and defense. In addition, they also determine many traits of the body as they are the last result of the gene expression.

The second and third blanks can be correctly filled up by DNA (deoxyribose sugar).

DNA is the genetic material in most of the organisms including humans. It contains all the information or blueprint for the synthesis of proteins which in turn help in determining the traits of a person.

The last blank can be filled up by the gene.

A gene refers to the unit of heredity which is present on the chromosome. It refers to the protein coding region of the DNA.