Subject-verb agreement

[SARDORBEK]

We know that pens, pencils and paper .... writing equipment.

a) is
b) are

As far as I know subject agrees with the verb, not with the object or complement.
In this sentence ----> are
But, isn't there one factor we have to consider,is there?
Doesn't the verb of the sentence agree in number with the third subject,
paper ---> in this case? Since paper is non-count, should I use singular verb?

Another question:
But In informal English can we use (a) answer, that's ----> is

Many thanks...

[Alan]

But, isn't there one factor we have to consider,is there?
Doesn't the verb of the sentence agree in number with the third subject,
paper ---> in this case?

No, it does not!
Only plural "are" is grammatical here.