Advice on new trees

We live in zone 8a and recently had some landscaping done in our backyard. Nothing fancy, some Bermuda sod laid, some trees planted (for privacy in a few years), pine straw laid, etc. We had 7 Emerald Green Arborviates planted and after a month they are starting to brown. I know based off a quick google search it could be one of three things:

1. Over watering
2. Under watering
3. The yearly browning/shedding the trees go through

Would love some thoughts and opinions from this sub on what we think is going on. Thanks!!