Although this is an easy question on Inequalities, there’s a trap answer which you need to be wary of. Since this is a ‘Must Be’ type of a question, any statement that is false once need not be considered as part of the answer.
Let us now look at the inequalities given.
a\(b^2\) > 0. \(b^2\) is always non-negative. However, in this inequality, since b cannot be equal to zero, \(b^2\) is definitely positive. But, \(b^2\) being positive does not make b positive. b can still be positive OR negative.
We can also say conclusively that a is positive.
If a and b are both positive, statement I is true.
But, if a is positive and b is negative, statement I is false. This is the case that is sometimes easy to miss and mark the answer as E, which is the trap answer.
a*c <0. This means that c is negative, since a is positive (as discussed already).
Statement II is definitely true since \(b^2\) is positive and c is negative.
Statement III is definitely true since a is positive and \(c^2\) is positive.
So, we can say statement II and III must be true. The correct answer option is D.
Hope this helps!