Janine set up an experiment to compare the amount of carbon dioxide produced by water plants. She used identical glass jars, M, N and O. Each jar contained the same amount and type of water plants and was filled with 500ml of water. An equal amount of liquid X was added to each jar of water. Only Jar O was coated with black paint as shown in the diagram below.

All the set-ups were placed near a window on a sunny day from 9 am to 5 pm.

The colour of water with liquid X will change when exposed to a different amount of carbon dioxide as shown below.

Amount of carbon dioxidehigher than normalnormalless than normal
Colour of water with liquid Xyellowredpurple

Which of the following shows Janine’s observation of the colour of water with liquid X correctly at the end of the experiment?

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