Acids have a high concentration of ...

a
C ions
b
H2O

c
OH- ions
d
H+ ions

Acids have a high concentration of [H⁺] ions

Explanation:

In order to know about the acids, a solution is acidic when pH < 7

As pH is lower than 7, the pOH > 7

When pH = 7, solution is neutral

When pH is greater than 7, solution is basic

pH = - log [H⁺]

pOH = - log [OH⁻]

Imagine a solution of pure HCl 0.2 M

HCl → H⁺ + OH⁻

[H⁺] = 0.2 M → pH = - log 0.2 → 0.69

pH + pOH = 14

pOH = 14 - 0.69 = 13.31

10^-pOH = [OH⁻] → 10⁻¹³°³¹ = 4.89ₓ10⁻¹⁴

In conclussion [H⁺] > [OH⁻]

pie chart because it is in percents ( % )