The correct answer to the question is option 4: Frame shift mutation. Thalassemia is a genetic blood disorder that occurs due to mutations in the globin genes responsible for making hemoglobin. These mutations can lead to a disruption in the normal reading frame of the gene, which results in an incorrect or incomplete protein being produced. This is known as a frame shift mutation, where the addition or deletion of a nucleotide shifts the reading frame of the DNA sequence. Frame shift mutations can have severe consequences on protein structure and function, leading to the symptoms associated with thalassemia. It is important to note that thalassemia can also occur due to other types of genetic mutations, such as point mutations, where a single nucleotide is changed, but frame shift mutations are a common cause.