The following consecutive staff readings were taken on pegs at 15m interval on a continuously sloping ground: 0.895, 1.305, 2.800, 1.960, 2.690, 3.255, 2.120, 2.825, 3.450, 3.895, 1.685, 2.050 (Stn. A:

a) 10.895m
b) 11.305m
c) 12.800m
d) 13.960m