The oldest rock layer in an undisturbed rock sequence occurs A;at the bottom of the sequence
B; below the sedimentary rock layer
C;below the unconformity
D;at the top of the sequence

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?