The
hummingbird combines upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, allowing them to reach a wing-flapping rate in excess of 50 strokes per second.
(A) hummingbird combines upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, allowing them to reach a wing-flapping rate in excess of
(B) hummingbird, combining upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, allows them to reach wing-flapping rates of over
(C) hummingbird, which combines upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, is allowed to reach wing-flapping rates of over
(D) hummingbird combines upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, allowing it to reach wing-flapping rates of over
(E) hummingbird, by combining upstroke wing muscles that are proportionally much larger than those of other birds with downstroke wing muscles that have the lowest recorded muscle strain of any flying bird, allowing them to reach wing-flapping rates in excess of