Which sentence uses quotation marks correctly?

a. We are all waiting for a break in the heat wave, "said Joanna," to begin planting our fall flower and vegetable gardens.

b. “When will you begin working on your research paper? asked my history teacher."

c. “If you turn right at the traffic light and drive for one block," explained the officer, "the city park will be on your left."

d. “My friend Rebecca said, "This semester I will be playing on the volleyball team, as usual.