Biological transmission differs from mechanical transmission in that biological transmission involves reproduction of a pathogen in an arthropod vector prior to transmission. works only with noncommunicable diseases. requires direct contact. occurs when a pathogen is carried on the feet of an insect. involves fomites

Biological transmission involves reproduction of pathogens in an arthropod vector prior to transmission. In terms of epidemiology, we can term a vector as an organism that is from infected to the uninfected. An infected organism which develops biological vector passes it to its host. For example a mosquito.

 A mosquito being a mechanical vector carries an infected organism to its host either through the legs or through the other body parts 

identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.