Error in Reasoning involves reading the argument and figuring out what is wrong with it. The correct answer choice will simply be a description of how the argument erred.
Example:
Argument: The coffee shop has freshly roasted its beans every day for the past two years, therefore next Thursday they will have freshly roasted beans.
Flaw: How can you know for sure that what happened before will continue to happen? They can change their roasting schedule, be closed altogether, not receive a shipment of beans, malfunctioning machinery, etc.
The correct answer choice can be described as follows:
Incorrectly assumes that was has been true in the past will continue to hold true in the future.
Argument evaluation involves reading the argument and then examining the answer choices, which typically take the form of a question. The correct answer choice will be such that when you provide opposite extreme answers, one of the answers should strengthen the argument and the other should weaken the argument.
Example:
Argument: I scored amazingly well on the LSAT, therefore this is the reason I have been accepted to Yale Law.
Argument evaluation answer choice: Does the LSAT score affect odds of admission?
Extreme answers: Yes and no. Well, if LSAT score affects odds of admission, this strengthens the argument. If it doesn't, this weakens the argument.
I hope this helps, please let me know if you have any other questions.
