Please help, really stuck

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time

Plz ! a scientist wants to produce a cow that makes a particular human protein in it’s milk the desired protein causes blood to clot and can be used to treat hemophilia (a blood clotting disorder). which of the following would be best for the scientist to use? a. genetic crosses. b. cloning. c. selective breeding. d. genetic engineering.

What pattern of migration do whales follow?