The correct answer is option D. There is only a relation between time and grades.
What is relation maths?
A relation is a mathematical term that describes the relationship between two sets of ordered pairs of values. Domain denotes the set of elements in the first set.
Here in the graph, we can directly find the grades of the students by selecting the time taken by the students to complete the test.
Therefore the correct answer is option D. There is only a relation between time and grades.
To know more about relations follow
https://brainly.com/question/25862883
#SPJ2