question_answer

If \[^{n}{{P}_{r}}=30240\] and\[^{n}{{C}_{r}}=252\], then the ordered pair \[(n,\,\,r)=\]

A)  \[(12,6)\]          

B)  \[(10,5)\]        

C)  \[(9,4)\]            

D)  \[(16,7)\]