In the Pressure-Flow Model, What Two Phenomena Starts the Flow

In the pressure-flow model, what two phenomena starts the flow of phloem contents?

A) active transport of sugar into sieve tubes, water follows by osmosis
B) water leaving sieve tubes by osmosis, followed by active transport of sugar into sieve tubes
C) active transport of water into sieve tubes, water entering companion cells by osmosis
D) water enters companion cells by osmosis, followed by active transport of sugar into sieve tubes
E) active transport of sugar into companion cells, water follows by osmosis