MECHANICS (errors in the use of apostrophes)
the answer is b.
A.At one time, "yes, ma'am" and "no, sir" were some boys' and girls' respectful responses to adults' questions.
B.Safeguarding the environment is not somebody elses responsibility; it is our's.
C.The Servicemen's Readjustment Act of 1944 is better known as the GI Bill of Rights.
D.Electrocardiograms (EKGs) are used to diagnose heart disease.