What are possible units of speed or velocity? A. km/hr B. sec/m C. kg/sec D. m/sec2

Speed or velocity is an expression that relates displacement or distance travelled per unit time. The SI unit for displacement is meter and kilometer is a derivative. The SI unit of time is seconds and a derivative is hour. Hence the answer among the choices is A. km/hr

(any unit of length) / (any unit of time)

is a unit of speed.

When combined with a direction, it's a velocity.

From the list of choices, only 'A' qualifies as a unit of speed.

'B' is either a dimensionless number (sec/minute)

or a unit of 'reciprocal speed' (sec/meter).

'C' is a unit of rate of change of mass. There's no name for it

'D' is a unit of acceleration.