Water retention and cracking of black soil together indicate which property?

Correct answer: Shrink and swell nature

The direct answer is A, shrink-and-swell nature. Black soil is clay-rich. When wet, its clay particles absorb water, expand and retain moisture; when dry, they lose water, contract and produce deep cracks. Thus the two observations—holding water and cracking on drying—are linked by one property, not by two unrelated causes. A is correct. B, biological growth of coral, occurs in suitable marine environments and does not describe soil. C, glacial accumulation, is the deposition of material by ice and cannot explain the characteristic behaviour of black soil. D, tidal influence, is associated with sea-level movement in coastal areas, not ordinary Deccan black soil. The Deccan is a major region of black soil and cotton is a common crop, but the asked property is shrink-and-swell behaviour. Exam cue: wet black soil swells; dry black soil cracks.