Final answer:
The Russellville varsity football team is now on the 10-yard line after the quarterback stumbles backward for 15 yards from the initial line of scrimmage, which was the 25-yard line.
Step-by-step explanation:
The question is asking about the position on a football field after a football quarterback stumbles backward. Given that the Russellville varsity football team started on its own 25-yard line and the quarterback stumbled back 15 yards, we need to subtract the yards stumbled from the original line of scrimmage to find the new position.
Starting position: 25-yard line
Yards stumbled backward: -15 yards
New position: 25 - 15 = 10-yard line
Therefore, the correct answer to the question is: a) 10-yard line.