Based on the description of the line graph showing tuition amounts for a university from 1996 through 1999, a valid claim could be:
"Tuition increased from 1996 to 1999."
This claim can be made if the line on the graph shows a rise in tuition amounts from the year 1996 up to 1999. If the exact tuition amounts for each year were provided, a more specific claim could be made, such as "Tuition was $8,500 in 1996 and increased to $10,000 in 1999." However, based on the general trend suggested by your description, the claim about an increase in tuition is appropriate.