Final answer:
The Transitive Property of equality is the correct answer, allowing the conclusion that m∠A = m∠D, based on given equalities between angles.
Step-by-step explanation:
The property described in the question is the Transitive Property of equality, which can be expressed as if a = b and b = c, then a = c. This property is a fundamental concept in mathematics, commonly used to establish that different measures, terms, or elements that have been demonstrated to equal a third common element are thereby equal to each other. In the example provided, where m∠A = m∠B, m∠B = m∠C, and m∠C = m∠D, the Transitive Property allows us to conclude that m∠A = m∠D. This property ensures consistency within mathematical reasoning and is a core aspect of concepts like geometric proofs and algebraic equations.