- All, who neither dance on tight ropes nor eat peanut butter, are tall.
- Creatures with spikey hair who look silly will go swimming if they do not dance on tight-ropes.
- A kangaroo looks silly wearing sunglasses.
- A smart creature will always do what he ought to do.
- No one ought to go swimming who looks silly and eats peanut butter.
- A smart driver wears sunglasses.
- Kangaroos that have sneezing fits are avoided.
- Short creatures who go driving have sneezing fits.
- No creatures ought to dance on tight-ropes if they have sneezing fits.
- All, who do not dance on tight-ropes and who are avoided, have spikey hair.
Therefore, no short kangaroos who are smart...
From statement 3, no smart kangaroo wears sunglasses. (I am assuming that "smart" and "look silly" are mutually exclusive). Also, we all know that kangaroos:
(a) do not have spikey hair ;
(b) cannot drive cars;
(c) cannot swim;
(d) and cannot dance on tightropes.
Accordingly.... from statement 1, short smart kangaroos must eat peanut butter. The only remaining items are: do our short smart kangaroos have sneezing fits, and are they avoided ? If the kangaroos are avoided, since they do not dance on tightropes, they would have spikey hair. So no short smart kangaroos are avoided. Therefore no short smart kangaroos have sneezing fits. So we complete the sentence as follows:
"Therefore, no short kangaroos who are smart forget to eat their peanut butter, which may be why they never have sneezing fits."