The end products of photosynthesis are oxygen, which the plants release, and carbohydrates, which become the plants' source of energy.
(The end products of photosynthesis; are; oxygen, which the plants release, and carbohydrates,) (carbohydrates; become; the plants' source of energy)
The end products of photosynthesis carbohydrates
are become
oxygen, which the plants release, and carbohydrates,
the plants' source of energy