What Is an Explanation for the Pectoral or Breast Meat

What is an explanation for the pectoral or breast meat of ducks being very dark in color?

A) Ducks use their wings for very short flights and need fast muscle fibers to power their take-offs.
B) Ducks are primarily swimmers and therefore do not need breast muscles full of "white meat."
C) Ducks employ intermediate muscle fibers for swimming and flying.
D) Ducks fly long distances and need myoglobin-rich slow muscle fibers to power high-endurance flights.