Which of the following sentences DO NOT use the semicolon correctly?

Arnold and Betsy hurried to feed the pigs; a huge storm was coming.


The pigs were still out in the field; therefore, Betsy and Arnold had to corral them into the barn for safety.


After feeding the pigs; Betsy and Arnold were caught in a downpour.


As they ran back to the house, Betsy and Arnold laughed that the pigs were safe but they were caught in the storm; it was truly an adventure.