I would say that the last one would be the most accurate.
Answer:

Step-by-step explanation:
Given
Cereal A


Cereal B


Cereal C


Required
Determine the expected value of grams of sugar
This is calculated by multiplying the probability and grams of sugar in each cereal.
The results of the products are then added together
i.e.




Hence;
The expected value of grams of sugar is 9 grams
Use the method rise over run (rise/run) that would get you 30/20 and that would equal to 1.5