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There’s a useful inequality property that says “If two inequalities have their inequality symbols facing the same way, we can ADD the inequalities.”
For example, if we know that...
a < b
c < d

...then we can ADD the inequalities to get: a + c < b + d
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GIVEN (I've rearranged the inequalities to create equivalent inequalities):
1 < r + s + t
s + t < 0

ADD the inequalities to get: 1 + s + t < r + s + t
Subtract s from both sides to get: 1 + t < r + t
Subtract t from both sides to get: 1 < r
If 1 < r, then we can be certain that Quantity B is greater

Answer: B

Cheers,
Brent