Study the chart and answer the question.
•
V
The Chinese began to use coal as fuel for heating homes and cooking food.
Steel was invented when coal was mixed with melted iron.
Which statement completes the cause and effect chart?
A
Food could not be cooked well enough using traditional heat sources.
B
Supplies of wood became scarce in Tang China.
c Wood was too valuable for trade to be burned by the Chinese.
D
Coal burned more efficiently than wood.
