In 2002, Baseball Pitcher Randy Johnson Began Wearing a Particular

In 2002, baseball pitcher Randy Johnson began wearing a particular metal-impregnated twisted rope necklace designed to "stabilize the electricity flow through the body." He claimed that it improved his pitching and his batting. One should question this claim because

A) the wearing of the necklace and improvement in performance may have been coincidental.
B) people are good at determining what affects their performance.
C) he failed to distinguish observation from inference.
D) personal testimonials are a reliable way to evaluate explanations.