Which of the following pairs is incorrect?

$A$ couple,both carriers for the gene of sickle cell anaemia,are planning to get married. What are the chances of them having an anaemic child (in $\%$)?

$A$ boy is colour blind. Among his two sisters,one is colour blind and one is a carrier (normal). Who is colour blind in his family?

Given below is a pedigree chart of a family with five children. It shows the inheritance of attached earlobes as opposed to the free ones. The squares represent the male individuals and circles the female individuals. Which one of the following conclusions drawn is correct?

Which of the following statements is incorrect regarding $Hemophilia$?

In an individual with phenylketonuria,there is an enzyme deficiency. This enzyme converts phenylalanine into ........ .