Hint: The most important function of the mitochondria is the production of energy from the food we take. It is termed as the "powerhouse" of the cell which produces energy in the form of ATP molecules. It is also involved in performing the cellular metabolism.
The mitochondria are defined as the membrane bound organelle present in the cell, which is responsible for energy generation in the form of ATP. With the involvement in ATP synthesis, mitochondria are also involved in cell growth, cell death and production of heat. Mitochondria performs cellular respiration for the production of ATP.
Now let us find solution from given options:
A)Cholodny-Went model : The Cholodny-Went model, came into existence in 1927, is a model describing tropism in germinating shoots of monocotyledons, which have tendencies for the shoot to grow towards light (phototropism) and the roots to grow downward (gravitropism).
B)Chemi-osmotic theory of Mitchell : The chemiosmosis is defined as the movement of ions down the electrochemical gradient between a semipermeable membrane bound structure. A most important example of this process is the production of ATP which occurs in the mitochondria of the cell.
C)Munch's mass flow theory : it is also known as pressure flow hypothesis. It describes the movement of sap through the phloem. It was given by Ernst munch.
D)Relay pump theory of Godlewski : It is also known as clambering and also relay pump theory. It describes movement of water upward in the water.
Hence, the correct answer is option (B)
Note: The chemiosmotic theory was provided by P.Mitchell. It starts with the photolysis of water thus producing protons on the inner side of the lumen. Whenever the electrons move through the photosystems, the transfer of protons takes place from the stroma to the lumen.