Statistics test

Following my last post I thought some clarification might be required in terms of relating percentages to each other so I pose a question:

You are walking along a road and reach a T-junction, both routes left and right will reach your destination and both are as easy and as long as each other so you have no particular cause to pick one over the other. A man sitting at the junction sees your indecision and pipes up.
"I wouldn't turn left if I were you there's a 50% chance of getting mugged"
"What about the other way?", you ask.
"That route has a 25% chance of you being mugged", he replies.

So not the obvious question of which route do you take but what is the difference in risk between the two? Is it -

a) 25%,
b) 50%, or
c) 100%.

Text your answers to... oh wait this isn't GMTV the question is vaguely difficult.

Okay got your answer it is of course d) all three depending on how you look at it. If you take the straight difference you end up with answer (a) which is accurate but pretty useless. Next is taking Relative Risk that is assuming one possibility is a certainty and comparing others to it. So if we make the 50% a certainty of 100% then the other route becomes 50% and the Relative Risk is 50% or answer (b)(pedants note it should be 1, 0.5 and 0.5 respectively). If we let the 25% stand as a certainty then the other route becomes 200% and the difference is 100% (again pendants note that it should be 1, 2 and 1 respectively and shouldn't be used as this raises a possibility above 1) answer (c) this should also make sense from a layman's point of view if I point out that one route is twice as risky as the other.

Okay the real answer is (b) but as mentioned (c) can also be seen as valid from one perspective

All good fun with numbers.