Answer: To design the circuit, follow these steps:
1. Start by drawing two 1.5V cells in series. Connect the positive terminal of the first cell to the negative terminal of the second cell. Label the positive and negative terminals accordingly.
2. Next, add a moisture sensor to the circuit. Connect one terminal of the moisture sensor to the positive terminal of the second cell. Connect the other terminal of the moisture sensor to one terminal of a switch.
3. Include an adjustable resistance in the circuit. Connect one terminal of the adjustable resistance to the other terminal of the switch.
4. Add a fixed resistance to the circuit. Connect one terminal of the fixed resistance to the other terminal of the adjustable resistance.
5. Include a transistor in the circuit. Connect the base terminal of the transistor to the other terminal of the fixed resistance. Connect the emitter terminal of the transistor to the negative terminal of the second cell. Connect the collector terminal of the transistor to one terminal of an LED.
6. Finally, connect the other terminal of the LED to the positive terminal of the first cell.
Make sure to label each component correctly for clarity.
Remember that this is a general guide, and the actual placement and arrangement of the components can vary depending on the specific circuit design and requirements.
:)