Let’s start with some rules
- An antecedent is a word toward the front of a sentence that a word farther along in the sentence (called the proform) refers to.
- Antecedents and proforms have to agree, which means they have the same grammatical form (both have to be singular or both plural, for example.)
- “Who” refers to people, “that” refers to non-people
Here are two examples, both from this article:
This news organization sat down with Crandall at Attivo’s headquarters to discuss the company’s work for customers, which include consumer-goods companies, tech firms, law offices, and government agencies.
Okay, is it the comany’s work or the company’s customers that’s included? It’s the customers! Even besides the list making sense as a list of customers, both “customers” and the proform, “include” are plural. So the grammar tells you, too.
There is this very advanced set of attackers that will use all sorts of social engineering to figure out how to get around the security systems.
“That” goes with non-humans, right? And attackers are human, right? So it should be “who will use etc.” right? But “set” is a math term, right? Non-human, right? Well… the context indicates that this is a set of humans, so I think “who” is still appropriate. (And “will use” can be either singular or plural, so that’s no help.) But that’s the editor in me.
What does the editor in you say?