How many of the following exhibit "+ +" interaction?
(a) Lichens
(b) Cuckoo and crow
(c) Frog and insects
(d) Lion and zebra
(e) Ticks on dog
(f) Fig and wasp

b‘++’ is where both species are benefited which is mutualism. Lichens are obligatory symbionts between fungi and algae. Figs and wasps are mutually benefited where wasps get ovipositioning site and food, fig trees are pollinated in return.

Frogs and insects; Lion and zebra - Predation

Cuckoo and crow; Ticks on dogs - Parasitism