Correct option: Root pressure is usually acidic because of active absorption.

Explanation for the correct option:

• When charged ion transverse through root hair using energy in the form of ATP is termed as active absorption.
• They occur against the concentration gradient.
• When due to active absorption excess of ions gets accumulated and are unable to get transpired efficiently with the same pace then in the root hair region osmosis starts takes place.
• Due to osmosis excess water get accumulated over the root hair region.

Explanation for the incorrect option:

• When there is increase in transpiration there would be no accumulation of ions.
• Low osmotic potential in soil would be seen as the outcome only when active absorption would have taken place.
• Passive absorption only acts when the concentration gradient is along the gradient of the cell.