Long description

Part (a): The first tree starts at Root. Root has two possibilities "a" and b (children of Root). "a" has two possibilities c and d. The second tree starts at U S B drive. U S B drive has two possibilities x and y (children of U S B drive). Part (b): The tree starts at the empty node. Empty node has two possibilities "a" and b (children of Empty node). "a" has two possibilities c and d. b has two possibilities x and y.