2. "Real numbers $a=b=c$" is the ( ) condition for the inequality $a^{3}+b^{3}+c^{3} \geqslant 3 a b c$ to hold with equality.
(A) Sufficient but not necessary
(B) Sufficient and necessary
(C) Necessary but not sufficient
(D) Neither sufficient nor necessary
2.A.
$$
\begin{array}{l}
\text { Given } a^{3}+b^{3}+c^{3}-3 a b c \\
=\frac{1}{2}(a+b+c)\left[(a-b)^{2}+(b-c)^{2}+(c-a)^{2}\right]
\end{array}
$$

we know that $a=b=c$ is a sufficient condition for $a^{3}+b^{3}+c^{3}=3 a b c$, but it is not necessary, because $a+b+c=0$ can also make the equality hold.