Which statement best describes a spring?

the top of the saturated zone
an underground layer of rock or sediment that holds groundwater
groundwater flowing naturally to the surface where it is lower than the water table
a vent in Earth’s surface that periodically ejects a column of hot water and steam

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit.there is a precise compatibility between the active site and the lactose molecule.specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.