McKean Corporation authorized 500,000 common shares in its articles of incorporation. On May 1, 2018, 100,000 shares were sold to the company's founders. However, on October 15, 2018, McKean repurchased and cancelled 20,000 shares to settle a dispute among the founders. On October 15, 2018, how many shares were outstanding?

a. 500,000 and 100,000

b. 100,000 and 100,000

c. 100,000 and 80,000

d. 80,000 and 80,000