@oliviapare123 No, because "some" can include just one. So, for example, imagine:

Group A contains three numbers: 1,2, and 3

Group B contains the number 1, so:

A ←s→ B

and Group C contains the number 2, so:

A ←s→ C

but, Groups B & C do not have any overlap, therefore B ←s→ C is invalid.