Assertion: Sedimentary nutrient cycles of phosphorus, calcium, magnesium, etc., are considered as imperfect
Reason: These cycles get more easily disrupted by local disturbances as the bulk of material remains in the relatively inactive and immobile reservoir on the earth's crust.

Answer

A

Explanation

Sedimentary nutrient cycles, e.g., phosphorus, calcium, magnesium are less perfet (or imperfect) as they get more easily disrupted by local disturbances as the bulk of material remains in the relatively inactive and immobile reservoir on the earth's crust (lithosphere). On the other hand, gaseous nutrient cycles are rapid and more perfect as compared to sedimentary cycles. It is because in gaseous nutrient cycles, e.g., carbon, hydrogen, oxygen, nitrogen, nutrients remain in circulation more or less uiniformly. In these cycles, nutrients self-adjust rather quickly because of large reservoir pool (atomsphere or hydrosphere).