Carry out the following osmosis experiment: Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup A empty (b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the following:
Explain why water gathers in the hollowed portion of B and C

Explanation

### Step-by-Step Solution:

1. **Understanding Osmosis**: Osmosis is the movement of water molecules through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration. In this experiment, the potato cells act as a semi-permeable membrane.

2. **Setting Up the Experiment**: You have four potato cups:
- Cup A: Empty
- Cup B: Contains 1 teaspoon of sugar
- Cup C: Contains 1 teaspoon of salt
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