Final answer:
A notion in Heraclitus' metaphysics was both patterned change and balanced opposition. He viewed the universe as perpetually changing yet governed by the logos, a universal principle providing order amidst this change.
Step-by-step explanation:
A notion in Heraclitus' metaphysics was d. both a and b, which refers to patterned change and balanced opposition. Heraclitus believed that all things are in constant flux, captured by the concept of becoming rather than being. He famously stated that you cannot step into the same river twice, indicating ongoing change. Heraclitus' idea of the logos also implies a kind of order or reason underlying the changes in the universe. Contrastingly, Parmenides taught that reality is changeless, and the true nature of reality is being, not becoming. Thus, Heraclitus' metaphysical views are characterized by the notion of patterned change and balanced opposition, where the dynamic state of existence is constantly in opposition but maintains a universal order.