How does the author define the San Andreas Fault?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.
The San Andreas Fault line is a fracture at the congruence of two major plates of the Earth’s crust, one of which support most of the North American continent, and the other of which underlies the coast of California and part of the ocean floor of the Pacific Ocean. The fault originates about six hundred miles south of the Gulf of California, runs north in an irregular line along the western coast to San Francisco, and continues north for about two hundred more miles before angling off into the ocean. In places, the trace of the fault is marked by a trench, or, in geological terms, a rift, and a small ponds dot the landscape. Its western side always move north in relation to its eastern side. The total net slip along the San Andreas Fault and the length of time it has been active are matters of conjecture, but it has been estimated that, during the past fifteen million years, coastal California along the San Andreas Fault has moved about 190 miles in a northwesterly direction with respect to the North American plate. Although the movement along the fault averages only a few inches a year, it is intermittent and variable. Some segments of the fault do not have move at all for long periods of time, building up tremendous pressure that must be released. For this reason, tremors are not unusual along the San Andreas Fault, some of which are classified as major earthquakes. Also for this reason, small tremors are interpreted as safe, since they are understood to be pressure that releases without causing much damage.
It is worth noting that the San Andreas Fault passes uncomfortably close to several major metropolitan areas, including Los Angeles and San Francisco. In addition, the San Andreas Fault has created smaller fault systems, many of which underlie the smaller towns and cities along the California coast. For this reason, Californians have long anticipated the recurrence of what they refer to as “the Big One”, a chain reaction of destructive earthquakes that would measure near 8 on the Richter scale, similar in intensity to those that occurred in 1857 and 1906. Such a quake would wreak devastating effects on the life and property in the region. Unfortunately, as pressure continues to build along the fault, the likelihood of such an earthquake increases substantially.
How does the author define the San Andreas Fault?
A. A plate that underlies the North American continent.
B. A crack in the Earth’s crust between two plates.
C. Occasional tremors and earthquakes.
D. Intense pressure that builds up.