Potential divider halves voltage when resistances are equal Steps:

• Voltage ratio is 3V/6V = 0.5.
• Formula: V_out = V_in × (R_LDR / (R_fixed + R_LDR)) = 0.5, assuming output across LDR.
• Solve: R_LDR = R_fixed.
• Fixed resistor in LDR circuits is typically 10kΩ to match LDR's operating range, so R_LDR ≈ 10kΩ to 100kΩ.

Why C is correct:

• Half voltage occurs when R_LDR equals R_fixed (≈10kΩ), placing it in the 10kΩ–100kΩ range typical for moderate light levels.

Why the others are wrong:

• A: Too low (bright light); R_LDR <10kΩ gives V_out <3V across LDR.
• B: Exactly 10kΩ assumes precise fixed value, but typical setups span the broader range.
• D: Too high (dark); R_LDR >100kΩ gives V_out >3V across LDR.

Final answer: C