Just one more clarification...I don't think you can have a "least common denominator" of a positive integer, so I'm going to treat this one as:
1) x is the least common denominator of 1/7 and 1/y (with y as a positive integer)
If that's the case, 1 isn't sufficient on its own, as x could be 7, 14, 21, etc. And if you look at what the decimals would be of x/55:
7/55 will be something really small (less than 1/7 and just over 1/8, so maybe around .13)
14/55 will just double that (so maybe around .27)
21/55 will triple the original (.3-something)
So we can tell that the hundredths digit will be different depending on which multiple of 7 x turns out to be.
Together, though, if x is a prime number that's the lowest common denominator of y and 7, then x must be 7 (anything else divisible by 7 is not prime). So x/55 = 7/55, and whatever that hundredths digit turns out to be, there will only be one. So the answer here would be C.
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