By which of the following techniques can we prove that phloem is the tissue responsible for food translocation?

Consider the following statements and choose the correct option from the codes given below:
$I.$ Loading of phloem is related to the increase of sugar in phloem.
$II.$ Active loading of sugar in the sieve tube of phloem is driven by a proton pump.
$III.$ Pressure may be positive or negative in sieve tube cells.
$IV.$ Water and solutes move through the sieve tube against the pressure gradient.
$V.$ Cytoplasmic strands pass through the holes in sieve plates and form continuous filaments.

When does the translocation of phloem sap in the phloem become bidirectional?

The food stored in the ripening fruit is derived from

Who proposed that the upward and downward movement of materials takes place through the phloem?

Explain the pressure flow hypothesis of translocation of sugars in plants.