Answer: The correct option is (B) 0.5.
Step-by-step explanation: We are given to use the following equation to determine the current (I) when the R is 20 ohms.
![I=(10)/(R)~~~~~~~~~~~~~~~~~~~~~~(i)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1tcyxcqwy98mhg1n6h54vc819i52bosres.png)
When R = 20 ohms, then from equation (i), we get
![I=(10)/(R)\\\\\\\Rightarrow I=(10)/(20)\\\\\\\Rightarrow I=(1)/(2)\\\\\\\Rightarrow I=0.5.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qbj2h3lyebf83f7eyq6f5j8k0d4a1s94vf.png)
Thus, the required current (I) is 0.5.
Option (B) is CORRECT.