How Does Rogue's Reliable Talent Work?

Question

So I'm making a Bard Rogue as a potential character for a D&D group I'm joining, and I was looking at Rogue at higher levels (debating between High Bard with Low Rogue or Low Bard with High Rogue) when I came across Reliable Talent PHB 96. It states

... Whenever you make an ability check that lets you add your proficiency bonus, you can treat a d20 roll of 9 or lower as a ten.

So here's the question. It specifically states "roll" not "result" which begs the question of is this ability referring to the end result being a 9 or lower (Including modifiers), OR the d20 roll without modifiers being a 9 or lower.

I personally think it is the roll before modifiers, since at level 11 you have a +4 Proficiency Bonus, but figured I'd ask here.

Answer 1

It's the roll before modifiers.

D&D 5th edition is very specific about its terminology. When it says a d20 roll, it means a d20 roll, not a result or a check.

When a D&D rule refers to rolling a number on a die, the rule means the number on the die. For example, rolling a 9 on a d20 means the number 9 on the die. In contrast, an ability check, a saving throw, or an attack roll includes the die roll and any relevant modifiers.
Tweet from Jeremy Crawford

Effectively, this ability means that you can never roll below 10 on the d20. Instead of a range of 1-20, your range is now 10-20. Hence "reliable" - you can be certain of at least average results every time.