When Blood Ca²⁺ Levels Fall Below Normal, in What Ways

Multiple Choice

When blood Ca²⁺ levels fall below normal, in what ways do the kidneys help restore them toward normal?

A) by increasing 1,25-dihydroxyvitamin D₃ formation, decreasing tubular phosphate reabsorption, and increasing tubular Ca²⁺ reabsorption
B) by increasing 1,25-dihydroxyvitamin D₃ formation, increasing tubular phosphate reabsorption, and increasing tubular Ca²⁺ reabsorption
C) by decreasing 1,25-dihydroxyvitamin D₃ formation, increasing tubular phosphate reabsorption, and increasing tubular Ca²⁺ reabsorption
D) Increasing 1,25-dihydroxyvitamin D₃ formation and increasing secretion of parathyroid hormone
E) by increasing renal secretion of parathyroid hormone and increasing bone resorption