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
The hummingbird is singular(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
The hummingbird is singular(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
tense error(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
No Remarks(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
No verb for main subject and pronoun errorIMO D