Final answer:
The best proof for Xavier's proportional claim would be either plotting a straight line on a graph starting at (0, 0), indicating a proportional relationship, or creating a table with equivalent ratios.
Step-by-step explanation:
To prove that Xavier's number of text messages is proportional to the amount he owes on his monthly phone bill, he should choose a method that demonstrates a consistent ratio between the two quantities. Option 1 is incorrect because it suggests a graph starting at (0.05), which does not make sense in this context. Option 2 is the correct approach, as it involves plotting data points to create a straight line on a graph starting at (0, 0), which would indicate a proportional relationship where if there are no text messages sent, no cost is accrued. Option 3 also serves this purpose by creating a table to test for equivalent ratios, which would show proportionality if the ratios are consistent. Option 4 is less direct, as it suggests creating equations based on the data which would show increase but not necessarily proportionality.