Muscle Contraction in Digestion

Steps:

• Identify the statement: Contraction of circular muscles pushes contents forward, describing a propulsion mechanism in the digestive tract.
• Recall peristalsis: Involves alternating circular and longitudinal muscle contractions to move food through the intestines.
• Match the description: Circular muscle contraction creates a wave-like motion that propels contents forward.
• Eliminate unrelated terms: Deglutination relates to swallowing, demarcation to boundary marking, and transpiration to plant water loss.

Why A is correct:

• Peristalsis is defined as rhythmic contractions of circular and longitudinal smooth muscles that propel intestinal contents forward via wave-like peristaltic waves.

Why the others are wrong:

• B: Deglutition refers to the swallowing process, not muscle-driven propulsion in the gut.
• C: Demarcation means marking boundaries, unrelated to muscle action or digestion.
• D: Transpiration is the evaporation of water from plant leaves, not an animal physiological process.

Final answer: A