Which one?
A. B. C. Or D?

Answer:
A
Step-by-step explanation:
[tex]6a^{2} - 24 = 0\\6a^{2} - 24 + 24 = 0 + 24 \\6a^{2} = 24\\\frac{6a^{2}}{6} = \frac{24}{6} \\a^2 = 4\\a = \sqrt{4} \\a = +2, -2[/tex]