This question already has an answer here:
Notice the italicized part of the following text:
In essence, when a retailer decides to build a larger store, it bets that it can use that extra square footage and expanded inventory to attract the higher volume of customers it needs to generate an acceptable return on investment.
If I am to put a relative pronoun between [the higher volume of customers] and [it needs], I surely can put relative pronoun that.
However, I want to know the type of the relative pronoun. Is the noun being modified by the relative clause the volume(a thing) or customers(people)?
Which of the following is acceptable?
- ~the higher volume of customers which it needs~
- ~the higher volume of customers whom it needs~