Answer: The statement that suggests that the shape of an enzyme determines its function, would be the fact that enzymes are specific to certain substrates, depending on the particular shape of an enzyme it can allow binding to specific substrates and allow for catalyzing that corresponding reaction
Most diving birds have (relatively) long necks and shorts legs, although their necks aren't as long as say herons, storks or egrets. Take the common loon for instance. Their necks can be up to half as long as their bodies but their legs are so short and set so far back that they are very awkward on land.