https://www.manhattangmat.com/forums/acc ... t5501.htmlAbove link says :
apparently we shouldn't be concerned with mathematical issues -- technically, "four times as likely as X" is 4X, while "four times MORE likely than X" is actually 5X. apparently, this is not a big deal on the verbal section.
may be as great, if not greater : I think if not greater is redundant in this sentence; here as great as is enough to suggest that chance is equivalent but not great.
Now choice E makes sense.
• may be as great, if not greater, while walking on the road than ( if not great is redundant + as.. than error)
• may be as great, if not greater, while walking on the road as ( if not great is redundant )
• may be greater while walking on the road, than ( the chance of mishap is as great as not greater than changing meaning )
• are at least as great while walking on the road as ( S -V error the chance is singular)
• may be at least as great while walking on the road as ( chance is equal or more looks fine)
If E had been written as "may be as great while walking on the road as" then it would have appear much convincing among other choices.