Which one of the following is an example of pleiotropy?

The gene,which controls many characters,is called

The phenomenon of pleiotropism refers to

In humans,the gene responsible for Phenylketonuria produces multiple phenotypic expressions,collectively known as a syndrome. This gene causes mental retardation,broad incisor teeth,skin pigmentation,and excessive sweating. What is this type of gene called?

Find the correct statement.
$(1)$ Generally a gene regulates a trait,but sometimes one gene has an effect on multiple traits.
$(2)$ The trait $AB$-blood group of man is regulated by one dominant allele and another recessive allele. Hence it is co-dominant.

Which of the following is not an example of pleiotropy?