Insects have open circulatory systems in which blood, or hemolymph, circulates through the body cavity rather than through closed blood vessels. Birds, like other vertebrates, have closed circulatory systems in which blood remains within arteries, veins, and capillaries as it circulates. How has this difference most likely influenced the evolution of birds and insects?
a. The open circulatory system of birds warms their entire body quicker, allowing them to live in colder climates more successfully than insects.
b. The closed circulatory system allows blood flow to increase to the flight muscles during flight, allowing insects to be better fliers than birds.
c. The greater efficiency of a closed circulatory system allowed birds to become larger than
insects.
d. The simplicity of the open circulatory system allows insects to have a higher metabolism than birds.