- A tricep is a kind of muscle
- Contracting is a kind of movement
- Hence, a tricep contracting is a kind of muscular movement

- Relaxing is a kind of movement
- A bicep is a kind of muscle
- So, a bicep relaxing is a kind of muscular movement

- A tricep contracting is a kind of muscular movement
- A bicep relaxing is a kind of muscular movement
- Therefore, a tricep contracting and a bicep relaxing are kinds of muscular movement

- A tricep contracting and a bicep relaxing are kinds of muscular movement
- Muscular movement helps animals move
- So, a tricep contracting and a bicep relaxing helps animals move

- A tricep contracting and a bicep relaxing helps animals move
- Straightening is a kind of movement
- So, a tricep contracting and a bicep relaxing helps animals straighten

- Biceps are part of an arm
- Triceps are part of an arm
- So, triceps and biceps are part of an arm

- Triceps and biceps are part of an arm
- The elbow is part of an arm
- Therefore, triceps and biceps and the elbow are part of an arm

- Triceps and biceps and the elbow are part of an arm
- If things are part of the same something, then those things are connected
- So, triceps and biceps are connected to the elbow

- A tricep contracting and a bicep relaxing helps animals straighten
- Triceps and biceps are connected to the elbow
- Therefore, triceps contracting / biceps relaxing causes a person 's elbow to straighten

Hence, triceps contracting / biceps relaxing causes a person 's elbow to straighten
Q: Which statement describes how muscles work to allow a person to extend an arm from a curled position by straightening the elbow?
Context:
- Relaxing is a kind of movement 
- Biceps are part of an arm 
- The elbow is part of an arm 
- A tricep is a kind of muscle 
- Straightening is a kind of movement 
- Triceps are part of an arm 
- Muscular movement helps animals move 
- A bicep is a kind of muscle 
- Contracting is a kind of movement 
- If things are part of the same something, then those things are connected