How might altering the glycosidic linkage in lactose affect its digestibility?

Changing the linkage from beta to alpha would make it more digestible by all mammals.

Changing the linkage from beta to alpha could make it indigestible by most mammals.

Changing the linkage from beta to alpha would make it indigestible only by humans.

Changing the linkage from beta to alpha would have no effect on digestibility.