3. Which of the following statements is true? a. Females cannot have hemophilia.
b. A colorblind boy's mother must carry the gene for colorblindness.
C. A sex-linked allele cannot be dominant
d. A colorblind boy's father must carry the gene for colorblindness.

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.

that is wrong, its not thymus.