The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find?

A) valine instead of glutamic acid in the sixth position
B) glutamic acid replacing valine in the first position
C) extensive amino acid substitutions
D) trinucleotide repeats
E) frameshift substitutions