use that or who

[Nary]

1) My father has a factory ...... makes bread.
2) The building ...... was on fire last year is being rebuilt now.
3) My father introduced me to the pearson ......designs a web page.
4) An Interior Designer is a person ...... designs the inside of a building

do we use that, who or which and why

[rewboss]

Use "who" for people and "which" for things. If the relative clause happens to be a so-called defining relative clause -- which is the case in all of your examples -- then you can use "that" for both people and things.

[Tdol]

Rewboss, out of curiosity, why do you say 'so-called'?

[Casiopea]

I guess if one holds true to past terminology, then so-called (adj., wrongly called the specified thing) works.

Terminology (past): restrictive, non-restrictive clauses
Terminology (present): defining, non-defining clauses

That's my guess . . .

[rewboss]

Rewboss, out of curiosity, why do you say 'so-called'?

Because that's what it's called.

"So-called" doesn't always mean "this is the wrong word for it". It can also mean, "There's this thing, and it has a complicated-sounding name, and this is what that name is".

[Tdol]

OK- I was just wondering if you meant it in the shouldn't-be-called-that sense.

[Casiopea]

Ah! In that case, sans the hyphen: so called.