Final answer:
The run-on sentence in this case is option c, which can be revised to correct the error by adding a coordinating conjunction or using a semicolon and transitional word.
Step-by-step explanation:
A run-on sentence occurs when two or more complete sentences are not separated by any punctuation. In this case, the only run-on sentence is option c: 'Every day the neighbor takes her dog on two walks she goes at night and in the morning.' This sentence can be revised by adding a coordinating conjunction like 'and' between 'walks' and 'she', or by separating the sentences with a semicolon and transitional word like 'however' or 'consequently'.