PT53 LR Section 2; Question 11 and 25 Forum

[Supernova]

PT53 - December 2007; Second LR Section; Question 11

Could someone explain to me why the correct answer here is (C) Businesspeople who already suffer from chronic insomnia are no more likely than businesspeople who do not accept assignments from their employers that require international travel.

I don't see how this strengthens the argument.

Also, could somebody explain Question 25 about Terry attending the meeting.

[Cambridge LSAT]

The speaker makes a causal claim based on correlative data. Choice C eliminates the possibility that a cause and effect relationship in the reverse direction explains the data.

international travel → chronic insomnia (conclusion)
chronic insomnia → international travel (choice C refutes this explanation)