A furniture retailer bought 100 identical chairs at a cost of $20 each. He sold some of the chairs within the first week

A furniture retailer bought 100 identical chairs at a cost of $20 each. He sold some of the chairs within the first week for $35 each. In the second week, he sold all the remaining chairs for $30 each. If his total profit on the sale of the chairs was greater in the second week than in the first week, which of the following can be the number of chairs sold by the retailer in the second week?
I. 30
II. 60
III. 80


A. I only

B. II only

C. III only

D. I and II only

E. II and III only

[spoiler]OA=C[/spoiler]

Source: e-GMAT