Compound A and C in the following reaction are `CH_(3)CHOoverset((i)CH_(3)MgBr)underset((ii)H_(2)O)rarr(A)overset(H_(2)SO_(4),Delta)rarr(B)overset("Hydroboration oxidation")rarr(C)`
A. identical
B. positional isomers
C. functional isomers
D. optiocal isomers