Jack has harvested a cereal crop. Without using fertilizer, how can he increase the field's soil fertility?

A. cultivate corn or oats

B. cultivate any leguminous plant

C. cultivate any kind of grass

D. keep the soil waterlogged

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answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]

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