Which of the following is a major difference between monocot and eudicot roots?

a. in monocots, the xylem and phloem are at the periphery, whereas in eudicots, the xylem and phloem are located near the center of the root.
b. eudicot roots lack xylem and phloem, whereas monocot roots have both xylem and phloem.
c. in eudicots, the xylem and phloem are at the periphery, whereas in monocots, the xylem and phloem are located near the center of the root.
d. monocot roots lack xylem and phloem, whereas eudicot roots have them arranged at the periphery of the root.

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).