Having studied small engine repair in night school, fixing the lawn mower was easy was a incomplete comparison .
Answer: D
Step-by-step explanation
A sentence is not complete when it has a dangling modifier.
This means that there is no action or subject in the sentence.
As a result, dangling modifiers occur due to wrong punctuation.
When you put a period in before the statement is complete, and then it will result in a fragment.
Further when writing a sentence while omitting one or 2 subject; you will be creating a fragment within that sentence.
Therefore in the given case, there is no subject.