There are two examples akin to this topic: one, an original from OG verbal and another simulated one from Kaplan
OG's version
Out of America's fascination with all
things antique have grown a market for bygone styles of furniture and fixtures that are bringing back the chaise lounge, the overstuffed sofa, and the claw-footed bathtub.
A) things antique have grown a market for bygone styles of furniture and fixtures that are bringing
B) things antique has grown a market for bygone styles of furniture and fixtures that is bringing
C) things that are antiques has grown a market for bygone styles of furniture and fixtures that bring
D) antique things have grown a market for bygone styles of furniture and fixtures that are bringing
E) antique things has grown a market for bygone styles of furniture and fixtures that bring
It is the market (a singular noun) that is bringing; Therefore OA is B.
2. Kaplan's version
Out of the public’s interest in the details of and conflicts in
other people’s lives have grown a booming market for “reality” television shows that are bringing “regular” people onto the television screen with increasing frequency.
1. other people’s lives have grown a booming market for “reality” television shows that are bringing
2. other people’s lives has grown a booming market for “reality” television shows that are bringing
3. another person’s life has grown a booming market for a “reality” television show that is bringing
4. other people’s lives has grown a booming market for “reality” television shows that is bringing
5. other people’s lives has grown a booming market for “reality” television shows that bring
Here also the subject noun is said to be a booming market: Hence -that is bringing- is the correct expression; per se Kaplan’s OA is 4.
Obviously the choice is B in the given topic from Princeton