In Magnesium-Deficient Plants, Older Leaves Become More Severely Chlorotic Than

In magnesium-deficient plants, older leaves become more severely chlorotic than younger leaves because:

A) magnesium is less phloem-mobile than chlorophyll.
B) magnesium is more phloem-mobile than chlorophyll.
C) younger leaves withdraw magnesium from older leaves.
D) older leaves withdraw magnesium from younger leaves.
E) magnesium is more mobile in younger leaves than in older leaves.