An organic compound has molecular formula $C_9{H}_{18}$. Its all carbon atoms are $s{p}^3$ hybridized and its all hydrogen atoms are identical. Its structural formula can be

The correct option is B
For a compound with molecular formula $C_c{H}_h{X}_x{N}_n{O}_o$
$\text{Degree of unsaturation}=(c+1)-\frac{h}{2}-\frac{x}{2}+\frac{n}{2}$
Where, X = Halogen
c=number of carbon atom
h=number of hydrogen atom
n=number of nitrogen atom
o=number of oxygen atom
In $C_9{H}_{18}O$
$\text{Degree of unsaturation}=(9+1)-\frac{18}{2}=1$
Compound has one degree of unsaturation, it can either one ring or one double bond.
All have $s{p}^3$ hybridized carbons so cannot have double bond thus one ring will be present.
Also, all hydrogens are identical as per question.
Hence coorect option is b.