Correct Answer - B
`:. DeltaOAB` should be equilareral
Now `angleOBC=90^(@) & AB=BC`
`rArr angleBAC=angle BCA =15^(@)`
`:. Angle BOF =30^(@)&angle BOC=45^(@)" {Delta OBC" is right isosceles"}`
`:. (angle BOF)/(angleBOC)=(30^(@))/(45^(@))=2/3" "{angleBOF=2angleBAF}`