(4) Given a regular tetrahedron with a volume of 54, if a new tetrahedron is formed by the centers of its four faces, then the volume of the new tetrahedron is ( ).
(A) 1
(B) 2
(C) 3
(D) 4
(4) By symmetry, the constructed tetrahedron is also a regular tetrahedron. Let the edge length and volume of the original tetrahedron be $a_{1}$ and $V_{1}$, and the edge length and volume of the constructed tetrahedron be $a_{2}$ and $V_{2}$. Then, by geometric properties, $\frac{a_{2}}{a_{1}}=\frac{1}{3}$, so $\frac{V_{2}}{V_{1}}=\left(\frac{1}{3}\right)^{3}$. Therefore, the volume of the constructed tetrahedron $V_{2}=\frac{1}{27} V_{1}=2$. Hence, the answer is B.