The function `f(x)=(sec^(-1)x)/(sqrt(x)-[x]),`
where `[x]`
denotes the greatest integer less than or equal to `x ,`
is defined for all `x in `
`R`
(b) `R-{(-1,1)uu{n"|"n in Z}}`
`R^+-(0,1)`
(d) `R^+-{n|n in N}`
A. R
B. `R-{(-1,1) cup {n|n in Z}}`
C. `R^(+) -(0,1)`
D. `R^(+) -{n|n in N}`