Correct Answer - A
In the ground state of hydrogen atom, suppose, `a_0=` bohr radius
`v_0=` velocity of electron in first orbit
`therefore` time taken by electron to complete one revolution, `T=(2pia_0)/(v_0)`
`therefore` current created, `I=("charge"(e))/("time"(T))=(ev_0)/(2pia_0)`