In a tansistor, IC = 100 mA and IE = 100.2 m

The correct answer is $\boxed{\text{B. 50}}$.

The value of $\beta$ (beta) is the ratio of collector current to base current. In this case, $I_C = 100 \text{ mA}$ and $I_B = 0.2 \text{ mA}$, so $\beta = \frac{I_C}{I_B} = \frac{100 \text{ mA}}{0.2 \text{ mA}} = 50$.

Option A is incorrect because $I_C$ is not equal to $I_B$. Option C is incorrect because $I_C$ is much greater than $I_B$. Option D is incorrect because $I_C$ is much less than $I_B$.