The most common adverb suffix is the suffix.
1. -long
2. -way
3. -ward
4. -ly

The correct answer is 4. -ly

Explanation:

To begin with, a suffix is one letter, multiple letters or a syllable added at the end of words that affect the meaning of it and also in some cases changes the category of the world. On the other hand, an adverb is a word that describes or modifies verbs by showing place, time, way, frequency, etc. In the English language, these type of words are mainly formed by adding the suffix "-ly" to adjectives as in slowly, carefully, rarely, absolutely, etc and because of this the suffix "-ly" is the one that identifies adverbs and it is the most common. Although other words such as here, never and down are also adverbs.

the answer is:  

he is voicing feelings shared by all humans regardless of race.

in paul laurence dunbar's poem "we wear the mask," he replicates the words mask and we to emphasize how people in general -not just black americans- hide their true feelings. he suggests the masks cover people's faces and eyes, which are the main parts that display their emotions. he also thinks people's pain conceal behind those masks, so that they cannot see reality and nobody is able to see one another's sorrow.