Answer:
C
Step-by-step explanation:
Simply match up the values for each choice and see which one fits the graph
A) for every hour, the graph shows an increae in $10 not $20 (Not valid)
B) For every 10 swimmers, the graph shows an increase in 1 lifeguard not 2 (not valid)
C) for 10 pieces of candy, there is an increase in $1 (VALID!!)
D) for every 2 km, the graph shows and increase in 20 min, not 30 min (not valid)
Hence only C fits the graph