The correct option is C 1353
Total no. of ways of selecting 4 books such that all the 4 books are not together = total no. of ways - total ways when all the books are together
Total no. of ways = 15C4
Total no. of ways such that all n books are consecutive =((a1,a2,a3,a4),(a2,a3,a4,a5),........,(an−3,an−2,an−1,an)
=n−3
For n=15, the number of ways =12
Hence the required number of ways=15C4−12=1353