On the first day of class, Professor Wallace tells her geography students that pop quizzes will be given at unpredictable times throughout the semester. Clearly, studying for Professor Wallace's surprise quizzes will be reinforced on a schedule.
a. fixed-interval
b. variable-interval
c. variable-ratio
d. fixed-ratio

b. variable-interval

Explanation:

the minoan civilization flourished in the middle bronze age on the island of crete located in the eastern mediterranean from c. 2000 bce until c. 1500 bce. with their unique art and architecture, and the spread of their ideas through contact with other cultures across the aegean, the minoans made a significant contribution to the development of western european civilization as it is known today. labyrinth-like palace complexes, vivid frescoes depicting scenes such as bull-leaping and processions, fine gold jewelry, elegant stone vases, and pottery with vibrant decorations of marine life are all particular features of minoan crete.  

so basically their unique way of ding arts, as well as architecture.

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.