Which sentence contains an error in the use of end marks or commas?
A.
The baby rabbit sat motionless so it was easy to pick it up.
B.
Strolling along the beach, we found many nice seashells.
C.
Mr. Nathan Mancy, Jr., will assume the presidency of the corporation on July 5.
D.
No, sir, I do not think the world revolves around me.