Chapter 7 - Circular Motion and Gravitation - Learning Path Questions and Exercises - Multiple Choice Questions - Page 258: 1

$\mathrm{c} )$ length $/$ length

Radian is basically a ratio of arc length and radius of a circle. Since both of them are a length, this means that radian is unitless so the answer is: Option $\mathrm{c} )$ length $/$ length