Resistance changes inversely affect PD with constant current

Steps:

• LDR resistance decreases as light intensity increases, since LDRs conduct better in brighter light.
• Thermistor resistance decreases as temperature increases, assuming a negative temperature coefficient (NTC) type.
• PD across a component is given by V = I R, with I constant.
• Thus, decreasing R in both cases decreases V.

Why D is correct:

• V = I R shows that constant I and decreasing R for both components reduce PD, matching LDR decreases, thermistor decreases.

Why the others are wrong:

• A: Wrong, as both resistances decrease, so PD decreases, not increases.
• B: Wrong, thermistor PD decreases with R drop, not increases.
• C: Wrong, LDR PD decreases with R drop, not increases.

Final answer: D