one claim made in the passage that illustrates the economic development of china under the song dynasty

Which of these statements properly demonstrates the angle addition postulate for the m∠afc m∠afc ? a. m∠afc=m∠afb+m∠bfd m∠afc=m∠afb+m∠bfd b. m∠afc=m∠afb+m∠bfc m∠afc=m∠afb+m∠bfc c. m∠afc=m∠cfd+m∠dfe m∠afc=m∠cfd+m∠dfe d. m∠afc=m∠afb+m∠dfc+m∠cfb m∠afc=m∠afb+m∠dfc+m∠cfb