A cell of emf $\epsilon$ and internal resistance r drives a current i through an external resistance R.
a) The cell supplies εi power  

b) Heat is produced in R at the rate $\epsilon$i 

c) Heat is produced in R at the rate $\mathrm{\epsilon i}\left(\frac{\mathrm{R}}{\mathrm{R}+\mathrm{r}}\right)$ 
d) Heat is produced in the cell at the rate $\epsilon$$i\left(\frac{r}{R+r}\right)$