Answer:
Option c.
Explanation:
This is the equation:
HF + H₂O ⇄ H₃O⁺ + F⁻ Ka: 3.5×10⁻⁴
So the HF is the weak acid which donates the proton to water, so the water becomes a base cause accepted it.
The hydronium will release the proton, then. It is the conjugate acid, from water and the F⁻ which would accept a proton to form the HF, it is the conjugate strong base.
In conclussion, HF is an acid, and F– is its conjugate base
