A science class tested ways to clean water after an oil spill. Each group of students was given 100 mL of vegetable oil, 100 mL of engine oil, and 800 mL of water in a rectangular plastic container. Each container also held five floating wooden cubes (5 cubic centimeters each) representing animals in the water. Each group was tasked with removing as much oil as possible in a 20 minute period, leaving “clean water” in the container, using whatever tools they brought to class. The results of the “clean-up” are presented in the table below.

Group
Vegetable oil removed (mL)
Engine oil removed (mL)
1
10
20
2
110
130
3
60
40
4
80
70

Based on the results above, which group’s data are obviously unreliable?
group 1
group 2
group 3
group 4