Answer: a.1680
Step-by-step explanation:
The number of permutations of n things taking m at a time is given by :-
[tex]P^n_m=\dfrac{n!}{(n-m)!}[/tex]
Similarly, the number of permutations of the first 8 letters of the alphabet taking four letters at a time will be :-
[tex]P^8_4=\dfrac{8!}{(8-4)!}\\\\=\dfrac{8\times7\times6\times5\times4!}{4!}\\\\=1680[/tex]
Hence, the number of permutations of the first 8 letters of the alphabet taking four letters at a time =1680
