Answer B?

Thanks for your message. Let's break down this argument. Premise: Larson cannot do assignment because she has an unavoidable scheduling conflict. Premise: Franks cannot do the assignment because he does not quite have the assertiveness the task requires. Conclusion: Task must be assigned to Parker, the only supervisor in the shipping department other than Larson and Franks. This is clearly a flawed argument. Why must the task be assigned to Parker if Larson and Franks cannot do it? We have nothing that states the only people who can complete this assignment are Larson, Franks and Parker. That is the missing assumption here, i.e. that Larson, Franks and Parker are the only people who can complete this assignment. Answer choice (B) states exactly that, "The task cannot be assigned to anyone other than a supervisor in the shipping department (i.e. Larson, Franks and Parker)." This is a Strengthen with Necessary Premise question so while (B) clearly strengthens the argument, let's make sure it is also required for the argument. When you negate (B), it becomes, "The task can be assigned to someone other than a supervisor in the shipping department." This clearly destroys the argument so (B) is the correct answer. Hope this helps! Please let us know if you have any other questions.

Why is C incorrect?

Why can't the answer be E ?

@ariella and @jayw, Great questions. As Mehran noted, this is a strengthen with a necessary premise question, so the answer we choose is required in order for the argument to stand a chance, whereas the incorrect answers are not required for the argument to hold. In order to see whether or not an answer choice is required, we can use the negation test to check whether the answer choice in question is needed for the argument. The reason this works is because the negation effectively takes the answer choice out of the argument. If the argument then falls apart, then we know that the answer choice we negated is required. (C)'s negation is Franks would not necessarily be assigned the task if Franks had the assertiveness the task requires. This negation does not wreck the argument because in the premises, we're given A REASON that Franks cannot do the assignment. For all we know, there could be other reasons that Franks cannot do the assignment and other reasons why he wouldn't be assigned the task. Since (C)'s negation doesn't wreck our argument, we know that (C) is not a necessary premise, so this answer choice is out. (E)'s negation is that someone who is not a supervisor in the shipping department has the assertiveness the task requires. Ok, but our argument is not wrecked with this negation. So what if someone else has the assertiveness required? There could be other requirements as well in order for someone to be able to do the assignment, so it doesn't matter if they merely have one of the necessary conditions in order to complete it. For this reason, we can eliminate (E), as its negation does not wreck the argument, so we know that it's not a necessary premise. Does this make sense? Let us know if you have any more questions!