Which statement correctly distinguishes $R$, $\overrightarrow{R}$, and $\hat{R}$ in Coulomb's law?

• A. $R$ is a unit vector, $\overrightarrow{R}$ is the scalar separation, and $\hat{R}$ is the force magnitude
• B. $R$ is the x-component of displacement, $\overrightarrow{R}$ is the y-component, and $\hat{R}$ is the total distance
• C. $R$ and $\overrightarrow{R}$ are both scalars, while $\hat{R}$ gives the magnitude of the force
• D. $R$ is a scalar distance, $\overrightarrow{R}$ is the displacement vector between charges, and $\hat{R}$ is the unit vector in the direction of $\overrightarrow{R}$

Answer: (D)