Question

A.)ii. and iii. B.)ii. C.)i. D.)i. and iv.

Answer 1

The answer is B) ii

The notation "p --> q" means "if p, then q". For example

p = it rains
q = the grass gets wet

So instead of writing out "if it rains, then the grass gets wet" we can write "p --> q" or "if p, then q". The former notation is preferred in a math class like this. 

So when is the overall statement p --> q false? Well only if p is true leads to q being false. Why is that? It's because p must lead to q being true. The statement strongly implies this. If it rained and the grass didn't get wet, then the original "if...then" statement would be a lie, which is how I think of a logical false statement. 

If it didn't rain (p = false), then the original "if...then" statement is irrelevant. It only applies if p were true. If p is false, then the conditional statement is known to be vacuously true. So this why cases iii and iv are true.