A. 4 7 = 9 T

B. 4 7 = T 9

C. 7 9 = T 4

D. T 4 = 7 9

Incorrect: This proportion uses unit rate to determine how long it would take to dig 9 holes if it took 7 hours to dig 4 holes.
Correct: This proportion uses unit rates to determine how long it would take to dig 9 holes.
Incorrect: This proportion uses scale factor to figure out how long it would take to dig 7 holes if 9 holes took 4 hours.
Incorrect: This proportion uses scale factor to figure out how long it would take to dig 7 holes if 9 holes took 4 hours.