In this circuit, the relationship between $$V_{i}  \&  V_{o}$$, is:

A

$$ V_{o}=V_{i} e^{\frac{v_{o}}{v_{r}}} $$

B

$$ V_{o}=V_{T} \ln \frac{v_{i}}{R_{s}I_{s}}$$

C

$$ V_{o}= v_{i}-I_{c} R_{s}$$

D

None of these