Edexcel internal resistance question

The correct answer is A. I understand that current decreases as total resistance increases, but don't understand the terminal p.d.

My thought process is that:
V = emf - Ir
So the decrease in I would increase V. But the increase in r would decrease V. Is something wrong with this? Or is it that r just increases more than I increases? If so, how am I supposed to figure this out?