This was a tricky question, many of the answers were intended to make you focus on facts that were not relevant. The text says only some, not all racecars have turbo boosted engines - and thus double-strap seat belts - therefore, not all cars have the double-straps and we do not know whether or not most racecars have the double strap. Concerning the non-racecars, it may be that there is not a single non-racecar that has a single strap seat belt, there is nothing prohibiting them from all having the double strap.

The question states that alumni donors are fans of the hockey team, but it does not explicitly state that they are only fans if the team wins.  The fact that a losing streak for the team would result in fewer donations only follows logically if we assume that these wealthy alumni are more likely to contribute when the hockey team is winning.  Some of the other choices could be true, but they are not necessary assumptions in order for the entire argument to be logical.

The basic argument of the passage is that athletes must practice and train to an extreme degree in order to reach an elite level. The argument is only coherent and logical with the assumption that natural talent alone is not able to make an athlete reach an elite level, which makes it a necessary assumption.

To answer this question, it is necessary to recognize that while appointment criteria are set forth for the board of directors, they are applied to the position of Treasurer. We are never told that a Treasurer is a member of the board of directors. Thus, the conclusion is only warranted if eligibility for appointment to the board is a necessary condition for appointment to the position of Treasurer.

The question takes a statement about a specific quantity of cheese and applies it to the fat content of all pizzas. It does not consider that pizza can contain different amounts of cheese or that other ingredients may contain fat. The one fact contained in the reasoning, that all cheese on pizzas has the same amount of fat, may throw some people off.

The argument is assuming that increasing the number of businesses moving to the state will also increase productivity in the state. While this might not seem like an assumption because the tax relief incentive has worked in other states, there might be other factors in the state legislator’s state which affect the outcome of their plan.

A necessary assumption is one that, if negated, would render the argument logically incorect. It is needed in order to fill some sort of logical "gap" from premise to conclusion.  The current gap in the argument is the leap from being able to discuss the aesthetic value of art (for which agreement of at least 2 people about the meaning is necessary) to being able to evaluate art objectively. The correct answer fills this gap by making discussion of aesthetic value a necessary condition for objective evaluation.  If this were not the case, the entire justification for the argument's conclusion fails.

The conclusion of this argument speaks to the ability to predict a race car's quickness in reaching maximum speed---horsepower alone won't permit an accurate prediction.  Why?  The argument states that the efficiency of the fuel-injection system varies among comparable cars.  This suggests that the fuel-injection system is a critical factor in a car's ability to reach maximum speed.  And that indeed is the unstated assumption.  The "efficiency of the fuel-injection system" is the key term in the evidence portion of the argument that is not stated in the conclusion, and it is that key term that must be contained in the assumption.  Any answer choice that does not mention that key term can be immediately eliminated.