The correct answer is the third one: Greek and Roman traditions.
The idea of Western culture is a modern concept, developed after the Italian Renaissance that retakes the values and ideas of Ancient Greece and Ancient Rome and applies them in a new context. This Western identity -linked to Christianity- was developed as opposed to the Oriental identity -linked to Islam- and other cultures found during the age of exploration in the Americas, Africa, and other continents. It is important to note that these roots -Greek and Roman traditions- are shared also by non-Western cultures.
Some of the most important features of Greek and Roman traditions taken by the Western culture are democracy (first developed in Ancient Athens), the Roman Republic, Greek philosophy and science, Roman law, and the Greek and Roman developments in art, architecture, and literature. For these and other characteristics, Greece and Rome many times are labeled as the cradle of Western civilization.
