Final answer:
The word form that correctly completes the sentence is 'allegation'.
Step-by-step explanation:
The word form that correctly completes the sentence is c) allegation.
An allegation is a claim or assertion that someone has done something illegal or wrong, typically without proof or before the matter has been fully investigated. In this sentence, several readers contacted the editor with the allegation that one of the writers had plagiarized material for a number of articles.
Other options:
- a) allegiance: Loyalty or commitment to a group or a cause. This word does not fit the context of the sentence.
- b) alleging: Present participle form of the verb 'allege,' which means to claim that someone has done something illegal or wrong without providing proof. While it has a similar meaning to 'allegation,' it doesn't fit the sentence grammatically.
- d) allegedly: An adverb used to indicate that a claim or assertion has been made without providing proof. While it is related to 'allegation,' it does not fit the sentence grammatically.