Answer:
B. point
Step-by-step explanation:
The type of mutation that causes sickle cell anemia is a point mutation. Specifically, it is a single nucleotide substitution in which adenine is replaced by thymine in the beta-globin gene, resulting in a change from glutamic acid to valine in the hemoglobin protein. This mutation causes the hemoglobin molecules to stick together and form stiff, sickle-shaped red blood cells, which can lead to various health problems.