Both Seagulls and wild geese are large birds. They're also similar in that both kinds of birds can fly over great distances. On the other hand, seagulls are scavengers, while wild geese aren't. Seagulls, for example, are often found around garbage dumps.

C. while and however

Explanation:

The options are :

A. and and similar.

B. both and difference.

C. while and however.

D. also and hand.

From the above passage, the words that show contrast can be seen in the following sentences:

"On the other hand, seagulls are scavengers, while wild geese aren't. "

The word "while" shows the contrast here.

"Seagulls, for example, are often found around garbage dumps. Geese, however, feed on things like seeds and insects."

The word "however" also shows contrast here.

Therefore, the correct answer is: C. while and however!