Which of the following mechanisms can explain the transport of sucrose from source to sink?

• A
  Osmotic movement of water into sugar-loaded sieve tube cells,which creates a higher hydrostatic pressure in the source than in the sink.
• B
  Tension created by differences in pressure potential between source and sink.
• C
  Active absorption of sucrose through sieve tube membrane driven by a specific pump.
• D
  Transpiration and active transport of sugar from source to sink.