Answer:
The correct answer is "Comma Splice"
Step-by-step explanation:
A "comma splice" is a type of grammar mistake and it occurs when two independant clauses are joined by a comma instead of a conjunction.
A way to fix the "comma splice" is to replace the comma by a conjunction, a semicolon or a subordinating clause.
In this case, there are two independant clauses "Jessica left the farm quickly" and " she arrived at the school an hour later." The comma between the two sentences is not strong enough to join the sentences. An alternative is:
Jessica left the farm quickly; she arrived at the school an hour later. (Use semicolon)