A substance is being secreted by the renal tubules if its

A. True A clearance value above the glomerular filtration rate (about 140 ml/minute) indicates secretion.

B. True Some of the unfiltered fraction must have been secreted.

C. False This suggests that the substance is normally reabsorbed by an active process.

D. False This can be explained by water reabsorption.

E. False Again, this can be explained by a relatively greater reabsorption of water.