Nhận biết (M1)

Although 60558 Echeclus and 2014 YX49 are both classified as centaur objects—outer solar system bodies in unstable orbits— they exhibit striking differences in __________ object 60558 Echeclus is considered an active centaur, showing sporadic comet-like activity (such as clouds of dust and gas on its surface), 2014 YX49, showing no such activity, is considered dormant.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A.

  behavior. The

• B.

  behavior: while the

• C.

  behavior, while the

• D.

  behavior; the