Exercise 1 solution

(a) Anisodactyl: three toes forward, one back. The most common arrangement.
(b) Zygodactyl: two forward, two back. Parrots and woodpeckers.
(c) Pamprodactyl: all four toes may point forward. Swifts.
(d) Syndactyl: second and third toes fused. Kingfishers and related Coraciiformes.

Not asked, but for completeness: heterodactyl (digits three and four forward, one and two back) is found only in trogons.