Zack's Coffeehouse schedules free poetry readings almost every Wednesd

This is indeed a tricky one - let me see if I can help .

The argument: We know that most Wed. Zach offers poetry reading. Whenever Zach offers poetry reading it offers half-price coffee all day.

To correctly infer we have to be careful not to make unwarranted assumptions. So avoid the following:

1a. Zack's only offers poetry readings on Wed.

2a. Zack's only offers drinks half-off when there is a poetry reading.

Instead, we have to be open to the following possibilities:

1b. There are poetry readings on other days of the week.

2b. We also have to keep in mind, that Zack's can offer half-price drink all day for some other reason besides poetry reading. Perhaps, Mondays is trivia day and all coffee is half off as well.

With that in mind let's eliminate:

A) Wednesday is the most common day on which Zack's offers half-priced coffee all day.

Perhaps every single Monday is poetry night. Or perhaps every Friday Zack's offers half-priced coffee.

B) Most free poetry readings given at Zack's are scheduled for Wednesdays.

Again, we do not know anything about the other days of the weeks. Even if Wed. is the most common day for poetry readings, if the number of poetry readings over the course of the week is greater than the number on Wed., we cannot make inference in (B).

C) Free poetry readings are scheduled on almost every day that Zack's offers half-priced coffee all day.

Refer to 2b: there can be other days that offer free poetry readings.

D) Zack's offers half-priced coffee all day on most if not all Wednesdays.

We know that Zack's has poetry readings on most Wed. Whenever it has poetry readings it has half-priced coffee. Therefore, it offers coffee most Wed. But what about the 'if not all' part? Remember, Zack's can offer half-price coffee for some other reason besides poetry readings. Perhaps, the Wed. in which there are no poetry readings, Zack's offers karaoke. And coffee is always half-off on karaoke nights. Therefore, it could be possible that Zack's offers half-priced drinks on all Wed. THE ANSWER

E) On some Wednesdays Zack's does not offer half-priced coffee all day.

This one is really tempting. But remember, just because Zack's doesn't have poetry readings on some Wed. doesn't mean that there isn't some alternate event in which coffee is also half-priced. So if Wed. is also Scrabble day, and on Scrabble day coffee drinks are half-priced all day, then we cannot infer (E).