As the frequency of the ac voltage across a capacitor approaches zero, the capacitive reactance of that capacitor:. a. approaches zero.
b. approaches infinity.
c. approaches unity.
d. none of the above.

b. approaches infinity

Explanation:

Because Capacitive reactance is given as Xc = 1/ωC

So we can see that the value of capacitive reactance and therefore its overall impedance (in Ohms) decreases to zero as the frequency increases acting like a short circuit.

Same as the frequency approaches zero or DC, the capacitors reactance increases to infinity, acting like an open circuit which is why capacitors block DC

it about 600 mph from what i calculated

a.   mass number from atomic number