Identify the Missing Particle in the Following Nuclear Equation $\begin{array} { c } 232 \\92\end{array}$

Identify the missing particle in the following nuclear equation:
228
90 Th ? 4
2 He + ?

A) $\begin{array} { c } 232 \\92\end{array}$ U
B) 232
89 Ac
C) 228
89 Ac
D) $\begin{array} { c } 228 \\88\end{array}$ Ra
E) 224
88 Ra