Question

The American robin is an appealing species partly because of its appearance and partly because it seems to be the ideal family bird. Robins are well known for their distinct reddish orange breasts. As with many species of birds, it is the male robin that has the brighter, more distinct markings. The female robin, who lays the beautiful greenish blue eggs, can lay up to fifteen eggs in a given year—not at the same time, however. Robins typically raise two broods a year. Both parents feed the babies after they have hatched. The young robins are ready to leave the nest in just fifteen days. While the female robin incubates her second clutch, the young from the first brood join the adult males in communal nocturnal roosts. When the young of the second brood are old enough, all the robins move to the communal roost.

Which of these words from the paragraph is NOT a transitional word?
a.
Partly
c.
While
b.
However
d.
When