The speed of light is the absolute limit for any object traveling through the universe. However, there may be a way to teleport, like Houdini,
from one part of the galaxy to another. In the same way that one can
fold a sheet of paper to bring two points together, scientists may one
day find a way to warp space itself. Warp travel would be a game
changer, opening up a vast new frontier for human beings.

- "a nonrestrictive clause functions as a modifier to a noun (that is an object, person or concept). these clauses can be described by the following three options: it is set off by comas, it contains a subject and a verbs and it adds nonessential information to the sentence.

for example, in "here is bill gates, who confounded microsoft software company" we can identify "who confounded microsoft software company" as a nonrestrictive clause modifying the noun bill gates. this clause can be describes as a nonrestrictive clause because it is separated by a comma, it adds nonessential information to identify who bill gates is and it must contain both a subject (who) and a verb (confounded)."

i am also pretty sure it is c

the answer is  loss : )                                                                                                 

heres the link