Which of the following special circulations has the widest range of blood flows as pa of its contributions to both the regulation of systemic vascular resistance and the modification of resistance to suit the organ's metabolic needs?

Skeletal muscle accounts for about 20% of cardiac output and systemic vascular resistance. During extreme physical exeion, more than 80% of cardiac output can be directed to contracting muscles; therefore, skeletal muscle resistance becomes the primary determinant of systemic vascular resistance during exercise.