Decreasing external resistance increases current but decreases terminal voltage

Steps:

• Total circuit resistance is external R plus internal r; decreasing R reduces total resistance.
• Current I = emf E / (R + r), so I increases as R decreases.
• Terminal potential difference V = E - I r; increasing I raises the I r drop.
• Thus, V decreases as I increases.

Why B is correct:

• Ohm's law and the formula V = E (1 - r/(R + r)) show V decreases with smaller R due to larger internal voltage drop.

Why the others are wrong:

• A: I increases, not decreases.
• C: I increases and V decreases, not the reverse.
• D: V decreases, not increases.

Final answer: B