Bob inherited 1,000 shares of ABC stock from his mother. His mother bought the shares at $3,000 ten years ago. The fair market value of the shares on the date of his mother's death was $25,000 ( no estate tax return needs to be filed). He sold shares in the current year at $28,500. What is the basis of the ABC shares that Bob inherited from his mother?

a) $28,500

b) $0

c)$3,000

d)$25,000