Answer
a) $a$ is Root
b) $a, b, d, e, g, h, i, o$
c) $c, f, j, k, l, m, n, p, q, r, s$
d) None
e) $d$
f) $p$
g) $ a, b, g$
h) $e, f, g, j, k, l, m$
Work Step by Step
a) $ "a"$ vertex is the root
b) $"a, b, d, e, g, h, i, o"$ vertices are internal because all these vertices have children.
c) $"c, f, j, k, l, m, n, p, q, r, s"$ vertices are leaves because it have no children.e
d) $j$ is not connected to any vertices lower than $j$ in the tree, so $j$ does not have any children.
e) $"d"$ vertex is the parent of h because $d$ connected to $h$ by an edge.
f ) $"p"$ vertices are siblings of $o$
g) $"a, b, g"$ vertices are ancestors of $m$
h) $"e, f, g, j, k, l, m"$ vertices are descendants of $b$
