Loams are soils with the best water and oxygen penetration because they have

Loams are soils with the best water and oxygen
  penetration because they have
  a. a high proportion of sand.
  b. a high proportion of silt.
  c. a high proportion of clay.
  d. high proportions of sand and silt and a low
  proportion of clay.
  e. equal proportions of sand, silt, and clay.

Question 2

Plants do not grow well in soils with a lot of clay
  because these soils
  a. hold onto and do not release water easily.
  b. are deficient in plant micronutrients and
  macronutrients.
  c. tend to absorb too much surface water.
  d. tend to become compacted and exclude air.
  e. do none of these.