Which sentence does not contain any punctuation errors?
a. following an introduction, ms. graves, the chair of the foundation, spoke, she received a standing ovation.
b. following an introduction, ms. graves, the chair of the foundation, spoke; and she received a standing ovation.
c. following an introduction, ms. graves, the chair of the foundation, spoke, and she received a standing ovation.
d. following an introduction, ms. graves, the chair of the foundation, spoke, and received a standing ovation.