8 ..... I was driving down the road, a football flew over a fence and hit my car.

Step 1: Analyze the sentence structure. The sentence describes an event that happened while another action was in progress.
Step 2: Choose the conjunction that indicates an action occurring during another ongoing action. 'While' or 'as' are suitable.
Step 3: Evaluate the options. Option C, 'As', can be used to indicate simultaneous actions or cause. Option B, 'Yesterday', is an adverb of time and doesn't fit grammatically. Option A, 'All day', also doesn't fit. 'As' is the most appropriate choice here to connect the two clauses.
Answer: As