What is the form of the underlined verb?

When aquinas realized that he could not find all the answers, he turned to

Public opinion polls are used in marketing

Identify the following sentence as simple, compound, complex, or compound-complex. even though most people think of africa as a desert, zimbabwe has a hot, tropical climate, so mangoes, passion fruit, pineapples, and avocados grow well there. a. compound b. simple c. complex d. compound-complex