Question

Directions for questions 37 to 41: Analyze the statements given and provide an appropriate answer for the questions that follow.

The number of airplanes equipped with a new anti-collision device has increased steadily during the past two years. During the same period, it has become increasingly common for key information about an airplane's altitude and speed to disappear suddenly from air traffic controllers' screens. The new anti-collision device, which operates at the same frequency as air traffic radar, is therefore responsible for the sudden disappearance of key information.

Which one of the following, if true, most seriously weakens the argument above?

• A. The new anti-collision device has already prevented a considerable number of mid-air collisions.
• B. It was not until the new anti-collision device was introduced that key information first began disappearing suddenly from controller's screens.
• C. The new anti-collision device is scheduled to be moved to a different frequency within the next two to three months.
• D. Key information began disappearing from controller's screen three months before the new anti-collision device was first tested.

Hint:

Look for the option that breaks the timeline the argument depends on, for example a fact showing the effect started before the supposed cause existed.

Answer 1

The Correct Option is D

The argument rests entirely on timing: both the device and the disappearances increased over the same two years, so the device must be the cause. The strongest weakener is whatever breaks that timing.

1. The device has already prevented a considerable number of mid-air collisions: this is about the device's benefit, not about whether it interferes with radar screens, so it leaves the causal claim untouched.
2. Disappearances began only after the device was introduced: this fits the timing the argument needs, so it supports the argument instead of weakening it.
3. The device is scheduled to move to a different frequency in future months: a future plan says nothing about whether the current frequency overlap explains the current problem.
4. Key information began disappearing three months before the device was first tested: if the problem existed before the device was even tested, the device cannot be the cause of that early disappearance, which directly breaks the causal timeline.

Only the fourth option attacks the timing the whole argument depends on. The other three either talk about a separate benefit of the device, support the timing instead of breaking it, or describe a detail, such as a future frequency change or airport size, that does not touch the causal claim for the past two years.

Let's summarize:

• An argument of the form "happened together, so one caused the other" is weakened by breaking the timeline.
• Disappearances starting before the device was tested means the device cannot be the sole cause.
• Details about the device's benefits or its future plans do not address the causal claim.

So the argument is weakened most by option 4.