How is the underlined pronoun in the sentence used?

there were 15 people among us who knew cpr.

underlined word: us

a.
subject

b.
possessive

c.
object of a preposition

d.
direct object

Which three of the following choices are advantages of using active voice a) engages readers b) less wordy c) conceals the subject d) less confusing e) object acted on is given importance

Which statements best evaluate the evidence in thisexcerpt? select two options.o the authors use a personal story to illustrate theargument that, despite new and ever-changing forms ofsocial media, arab american print and broadcast mediaare stronger than ever.the authors use data about the types and effectivenessof social media to support the argument that socialmedia is driving arab american broadcast media out ofbusiness.the authors use a quotation from an expert to supportthe argument that social media has been both and hazardous for the arab american news mediao the authors use a quotation from an eyewitness tosupport the argument that the arab american newsfree daeros challsave and exitnextsubmit

What is wrong with they follow citation of a book with two authors