Why Every real inductor has distributed capacitance between its turns, so it behaves like an inductance in parallel with a small capacitor. At the self-resonant frequency the two reactances cancel and the impedance peaks; above that frequency the winding capacitance dominates and the part acts like a capacitor, with impedance falling as frequency rises. This is why RF chokes and coils are only usable well below their self-resonant frequency.
Watch out The choice saying reactance increases describes the inductor below self-resonance, where XL = 2*pi*f*L keeps climbing with frequency; above self-resonance the net impedance drops instead.
Past self-resonance, the stray turn-to-turn capacitance wins: the coil stops acting like a coil and acts like a cap.