If the rate of soil loss does not exceed the rate of soil formation it is called

Correct option is A

When soil loss occurs at a rate equal to or less than the natural rate of soil formation, it maintains equilibrium. Such soil erosion is a slow and continuous process that does not significantly affect soil productivity. This balanced process is known as natural erosion.
Information booster: Natural erosion has been occurring since the formation of land surfaces and is part of natural geomorphic processes. It usually occurs due to natural agents like wind and water under undisturbed conditions. Soil productivity remains stable because new soil forms at a rate comparable to soil loss. In contrast, human activities often disturb this balance and lead to accelerated erosion.
Why other options are incorrect: (b) Accelerated erosion occurs when soil loss exceeds soil formation due to human interference. (c) Both 1 and 2 is incorrect because the definitions of natural and accelerated erosion are opposite. (d) None of these is incorrect because natural erosion correctly fits the statement.