The theory put forth by Thaine $(1964)$ is of

According to the pressure flow hypothesis:
$A.$ Phloem loading produces a hypertonic condition in the sieve tubes.
$B.$ Water potential gradient facilitates the mass movement in the phloem.
$C.$ Phloem unloading is a passive process.

"Girdling Experiment" was performed by plant physiologists to identify the plant tissue through which:

In what form are carbohydrates generally translocated as nutrients in plants?

Assertion : Long distance flow of photoassimilates in plants occurs through sieve tubes.
Reason : Mature sieve tubes have parietal cytoplasm and perforated sieve plates.

In phloem,the flow is always from