$\text{CORPORATION:}$ Total $11$ letters, and $R-2,O-3$
Vowel: $O – 3, A-1, I-1$
Now, $\underbrace{\underbrace{OOOAI}_{\frac{5!}{3!}}\;\;CRPRTN}_{\dfrac{7!}{2!}} \implies \dfrac{7!\cdot 5!}{3!\cdot 2!} = \dfrac{5040\cdot 120}{12} = 50400.$
So, the correct answer is $(D).$