The Mutation That Causes SCD Causes What Kind of Change

The mutation that causes SCD causes what kind of change in the structure of hemoglobin?

A) decreases heme-binding ability
B) fewer chains of amino acids (trimeric rather than tetrameric structure)
C) a single amino acid substitution that alters the structure of the tetramer
D) addition of a single amino acid that causes a longer protein subunit
E) loss of a single amino acid that causes a frameshift and premature stop codon