The step(s) necessary for determining the percentage of water absorbed by raisins is/are:

To calculate the percentage of water absorbed by raisins accurately using the formula:

$$\text{Percentage of water absorbed} = \frac{W_2 - W_1}{W_1} \times 100$$

(where $W_1$ is the initial weight of dry raisins and $W_2$ is the final weight of swollen raisins), all experimental conditions must be strictly controlled:

1. Complete immersion (Step 1): Ensures that the entire surface area of the raisins is in contact with water, allowing uniform and maximum endosmosis.
2. Sufficient soaking time (Step 2): Gives enough time (2-3 hours) for the water to diffuse through the selectively permeable membrane until the cells become fully turgid.
3. Gently wiping dry (Step 3): Removes external surface water so that the final weight ($W_2$) represents only the weight of the raisins plus the water absorbed inside them.

Since all three steps are absolutely necessary for an accurate and reliable result, Option 4 (All of the above steps) is correct.