Which of the following diseases is genetically linked?

If a colour blind woman marries a normal visioned man,their sons will be

If a colour-blind man marries a woman who is homozygous for normal colour vision,the probability of their son being colour-blind is

$A$ couple,neither of whom has sickle cell anemia,has a first child who is affected by sickle cell anemia. What is the probability that their second child will have sickle cell anemia (in $, \%$)?

Given below is a pedigree chart showing the inheritance of a certain sex-linked trait in humans. The trait traced in the above pedigree chart is

Explain thalassemia.