___________ , considered a perfect soil, is a mixture of silt, clay and sand:

A. 0.9869 atm
B. Wt. Of a 1020 cm water column
C. 75.01 cm high mercury column
D. All of these

A. Hiltner
B. Aristotle et al.
C. A.Q khan
D. Helium. S. Denial

A. Sedimentary rocks
B. Igneous rocks
C. Alluvial rocks
D. All the above

A. Indiscriminate felling of trees
B. Over grazing
C. Mismanagement of irrigation syste
D. All of these