The sentence is discussing the impact of the present wanton display of riches on the morality of our society.

The verb "display" is in the present tense, indicating an ongoing action. Therefore, we need a verb form that matches the present tense and agrees with the subject "display."

Option A. will be affecting: This is in the future tense and does not match the present tense of the sentence.

Option B. are affecting: This is in the present tense, but it uses the plural form "are" instead of the singular form "is" that agrees with the subject "display."

Option C. is affecting: This is in the present tense and agrees with the subject "display." It correctly indicates that the present display of riches is currently impacting the morality of our society.

Option D. was affecting: This is in the past tense and does not match the present tense of the sentence.

Option E. had been affecting: This is in the past perfect tense and does not match the present tense of the sentence.

Therefore, the most appropriate option is C. is affecting.