ACT scores

I just received my December ACT scores, and got:

English: 34
Maths:32
Reading:35
Science:31

ELA: 31 STEM: 32 Composite: 33

However in my September test I got

English:30
Maths:32
Reading:32
Science:35

ELA: 28 STEM: 34 Composite: 32

I’m wondering which scores to send (to Stanford). I understand that the December score is overall better, but I mention in my application that I am looking towards engineering as my major. should I therefore send the scores that have better STEM and science scores but worse overall, or should I send the September scores? Please anyone that has any sort of advice or opinion this would really help.

I think that Stanford requires all scores to be sent. Many highly selective schools have this policy.