People with full blown sickle-cell disease will experience harmful effects such as, red blood cells break down, clump, and clog blood vessels. broken cells can accumulate in the spleen. this can lead to many symptoms such as physical weakness, heart failure, pain, and brain damage. having so many symptoms can be explained by

a. the polygenic nature of sickle-cell disease
b. side effects of the drugs used to treat sickle-cell disease
c. a bacterial infection interacting with the sickle-cell allele
d. the sickle-cell allele can impact many different body systems

Answer :a. the polygenic nature of sickle-cell disease

Explanation:

SS is a genetic disorder in which more than two genes control a single character. Contrary to  single gene to a trait. It  exhibit an abnormal clinical heterogeneous traits   for Mendel    inheritance with multiple factors exerting influence on an individual disease outcome. Therefore multiple complications arises with symptoms

d. the sickle-cell allele can impact many different body systems

Explanation:sickle cell anaemia is the shortage of red blood cells.red bloods cells functions to carry oxygen through out the body aided by the haemoglobin.when however a person has sickle cell anaemia,his red blood cells become abnormal.they are no longer flexible and round ,they become stiff and sickle-shaped.when this changes in the red blood cell occurs,it is no longer flexible to pass through the blood vessels,causing the blockage of the vessels and the red blood cells break apart easily ,causing its shortage in the body.as body organs need oxygen to survive, people with sickle cell anaemia tends to have organ failures,pain crises , infections etc.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)

it would be heredity