uppose that we have two relationsStudent$($StudentID$,$ StudentName, DegreeScheme$)$Enrollment$($StudentID$,$ ModuleID, Year$)$and the following query:Select count $(*)$From Student, EnrollmentWhere $($Student$.$DegreeScheme $=$Computing$$Or Student.DegreeScheme $=$Accounting$)$And Student.StudentID $=$ Enrollment.StudentID;i$.$Explain how a B$-$tree index may be used to speed upthe execution of this query.