Why do plant cells have large vacuoles?

They have large vacuoles because they need and store more water.

In plant cells, the vacuoles are much larger than in animal cells. When a plant cell has stopped growing, there is usually one very large vacuole. Sometimes that vacuole can take up more than half of the cell's volume. The vacuole holds large amounts of water or food.

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b is the best answer for this question.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.