Gretchen purchased a home on October 1st for $300,000. 18 months after she purchased her home, her employer transferred her to another city, which is 2,000 miles away. Gretchen decided to sell her home for $340,000. How much of Gretchen's gain from the sale of her home can be excluded from gross income?

a) $10,000 b) $30,000 c) $40,000 d)$ 0