Final answer:
Caden poured 1 1/3 pints onto his plants, which is calculated by subtracting the remaining water from the original amount.
Step-by-step explanation:
Caden originally had 3 pints of water in a pitcher. After watering his plants, he was left with 1 2/3 pints. To find out how many pints Caden poured onto his plants, we need to subtract the amount of water left from the original amount.
3 pints - 1 2/3 pints = 1 1/3 pints. Therefore, the amount of water Caden poured onto his plants is 1 1/3 pints, which corresponds to option B.