How many ways can six books be placed on a shelf from left to right?
a
\large 6!
b
\large _6P_1
c
\large _6C_6
d
\large 6+5+4+3+2+1
a
\large 6!
b
\large _6P_1
c
\large _6C_6
d
\large 6+5+4+3+2+1