Question

3 grooves AB,AC and AD are made in a circular disk lying in a vertical plane 3 particles B,C and D constrained to move along path AB,AC and AD respectively are released from point A.Particle B reaches point B in time tB,particle C reaches point C in time tC and particle D reaches at point D in time tD.Then which of the following statements is incorrect
tB=tC=tD
tB>tC=tD
tC>tB>tD
tD=tB>tC