A disease that occurs due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globin chains :-

The correct option is A Sickle cell anaemia
Sickle cell anemia occurs when GAG becomes GUG in the DNA causing the sixth amino acids is valine instead of glutamic acid in the beta globin chain.

Thallesemia , Phenylketonuria and Haemophilia are Mendelian disorders that are caused when their parents are carriers. They are chromosomal diseases and not caused by mutation .

So the correct answer is ' Sickle cell anemia'.