LSAT 122 – Section 1 – Question 02

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Question
QuickView
Type Tags Answer
Choices
Curve Question
Difficulty
Psg/Game/S
Difficulty
Explanation
PT122 S1 Q02
+LR
+Exp
Resolve reconcile or explain +RRE
A
8%
155
B
89%
163
C
0%
148
D
1%
156
E
1%
156
127
138
149
+Easier 146.495 +SubsectionMedium

A study of plaque buildup on teeth used three randomly assigned groups of people who brushed their teeth twice a day for a year. People in Group 1 used the same toothbrush all year. People in Group 2 used the same toothbrush all year but sterilized it each month. People in Group 3 used a new, sterile toothbrush each month. At the end of the year, people in Groups 1 and 2 had the same amount of plaque buildup as each other, while people in Group 3 had less plaque buildup.

"Surprising" Phenomenon
Why did people in Groups 1 and 2 have the same amount of plaque buildup after a year while people in Group 3 had less?

Objective
The correct answer choice must provide a similarity between people in Group 1 and Group 2 that helps explain why they had the same level of plaque buildup, a difference between people in Group 3 and those in Groups 1 and 2 that helps explain why people in Group 3 had less plaque buildup, or both.

A
The buildup of plaque on teeth, which brushing twice a day helps to prevent, is accelerated by the growth of bacteria on toothbrushes that remained unsterilized for more than a month.
People in Group 2 sterilized their toothbrushes monthly but had the same level of plaque buildup as those in Group 1. Also, people in Groups 2 and 3 used sterilized toothbrushes to begin each month, but they had differing buildup levels. (A) explains none of these things.
B
The stiffness of the bristles on new toothbrushes, which the mechanical action of brushing destroys after several months, inhibits the buildup of plaque.
This gives us a key difference between the experience of people in Group 3 from the experience of people in Groups 1 and 2. Only those in Group 3 used a new toothbrush each month, so (B) helps explain why people in Group 3 had less plaque buildup than those in Groups 1 and 2.
C
The people who did the study measured the amount of plaque buildup by a new method not usually employed by dentists.
This new method was used to measure the plaque buildup of all people in each Group, so it doesn’t help explain our phenomena.
D
Before they joined the study, some of the people in Group 3 had been in the habit of brushing their teeth only once a day.
What people were doing before the study is irrelevant. We want to know why people in Groups 1 and 2 saw the same level of plaque buildup during the study, people in Group 3 saw less buildup than those in Groups 1 or 2, or both.
E
The people in Group 2 and Group 3 brushed their teeth as vigorously as did the people in Group 1.
(E) gives us a similarity between all 3 groups. It explains nothing about why Groups 1 and 2 saw the same amount of plaque buildup even though they took different approaches to teeth cleaning nor why people in Group 3 saw different levels of buildup than those in Groups 1 and 2.

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