Complete the following reaction sequence :
`CH_(3)-overset(O)overset(||)C-CH_(3)overset((i)CH_(3)MgBr)underset((ii)H_(2)O)rarr(A)overset("Na metal")underset("ether")rarr(B)overset(CH_(3)-Br)rarr(C)`
A. Identical
B. positional isomers
C. functional isomers
D. optical isomers