Which vitamin is important for the absorption of calcium and phosphorus?

Filament materials are chosen primarily for their

a. atomic number. b. high melting points. c. ability to vaporize easily. d. high boiling points.

________ is a refractive disorder in which irregularities in the curvature of the cornea cause light not to focus on the retina but to spread out over an area, causing overall blurring of vision.

A. Astigmatism B. Myopia C. Presbyopia D. Strabismus