Reading passage: Scientists consider both landslides and surface-creep movement essential in the formation of rock glaciers. Evidence of landslides can be distinguished from that of surface-creep movement because landslides leave a deeper and more definite surface of rupture, partly due to their faster rate of movement. Those studying the origins of rock glaciers have noted that some glaciers are well-defined, while others are not; that is, some show evidence of deep ruptures, while others do not. Given the information in the passage, which of the following may be concluded about rock glaciers? Choose one answer:

A. The author loves to attend theatrical productions.

B. The author also enjoys concerts and movies.

C. The author prefers musical comedies

D. The author finds theatre seating comfortable

A. They would rather be at a concert.

B. They are overly emotional and dramatic.

C. They enjoy the décor of most theaters

D. They go to the theater as often as possible.

A. Not all rock glaciers originate in the same way.

B. Landslides initiate the formation of rock glaciers, then surface-creep movement follows.

C. Neither landslides nor surface-creep movement account for the formation of rock glaciers.

D. While the definition and depth of rupture can be measured at rock glacier sites, the rate of movement cannot.