The tables below show four sets of data:

set a
x
1
2
3
4
5
6
7
8
9
y
10
9
8
7
6
5
4
3
2
set b
x
1
2
3
4
5
6
7
8
9
y
3
4
5
6
7
8
9
10
11

set c
x
1
2
3
4
5
6
7
8
9
y
8
6
5
4
3.5
3
2.5
2
2
set d
x
1
2
3
4
5
6
7
8
9
y
1
2.5
2.5
3
4
5
6
8
9

for which set of data will the scatter plot represent a positive linear association between x and y?

set a
set b
set c
set d