Which of the following involve analog quantities and which involve digital quantities?

(a) Elevation using a ladder

(b) Elevation using a ramp

(c) Current flowing from an electrical outlet through a motor

(d) Height of a child measured by a yard stick ruler

(e) Height of a child measured by putting a mark on the wall

(f) Amount of rocks in a bucket

(g) Amount of sand in a bucket

(h) Volume of water in a bucket