Choose the sentence that does not include a usage error.

A) Because the student did not see any author information on the website, he incorrectly implied that he did not need to credit the source in his assignment.
B) Because the student did not see any author information on the website, he incorrectly inferred that he did not need to credit the source in his assignment.

B is correct

http://grammarist.com/usage/imply-infer/

To determine if sentence A or sentence B does not include a usage error, let's examine the words "implied" and "inferred" in each sentence.

The verb "imply" means to suggest or hint at something without explicitly stating it. In sentence A, "he incorrectly implied" means that the student suggested or hinted at something incorrectly without explicitly stating it.

The verb "infer" means to deduce or conclude something based on evidence or reasoning. In sentence B, "he incorrectly inferred" means that the student came to a conclusion or made a deduction incorrectly based on evidence or reasoning.

Both "implied" and "inferred" are correctly used in their respective sentences. So, both sentence A and sentence B are grammatically correct and do not contain a usage error.