GMAT Data Sufficiency (DS) | Re: Is a>b

I will go with E.
best approach - number testing...it helped me crack this question in under 50 seconds.
1. say a=3 and b=2 -> a>b. or say a=2, b=3 -> holds true the statement, but a<b - 2 options - not sufficient.
2. says a and b are negative - nothing new.

1+2
b^4 is always positive when b is negative, so it will always be a<b^4, but we don't know anything about the relation between a and b.

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