Which of the following pairs has muscles which are on the same side of the body?  

• A. Rectus femoris & biceps femoris. 
• B. Rectus femoris & pectoralis major. 
• C. Biceps brachii & triceps brachii. 
• D. Tibialis anterior & gastrocnemius.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the anatomical positions of each muscle mentioned in the pairs. Identify which side of the body (anterior/front or posterior/back) each muscle is located on.
2. Step 2: For the pair 'Rectus femoris & biceps femoris,' note that the rectus femoris is located on the anterior (front) thigh, while the biceps femoris is on the posterior (back) thigh. Therefore, they are on opposite sides of the body.
3. Step 3: For the pair 'Rectus femoris & pectoralis major,' recognize that both muscles are located on the anterior (front) side of the body — rectus femoris on the front thigh and pectoralis major on the chest.
4. Step 4: For the pair 'Biceps brachii & triceps brachii,' observe that the biceps brachii is on the anterior (front) side of the upper arm, while the triceps brachii is on the posterior (back) side of the upper arm, so they are on opposite sides.
5. Step 5: For the pair 'Tibialis anterior & gastrocnemius,' note that the tibialis anterior is on the anterior (front) of the lower leg, and the gastrocnemius is on the posterior (back) of the lower leg, meaning they are on opposite sides.