Kara owns a salt-water aquarium in which the level of salinity, or concentration of salt in the water, must be maintained within a narrow range.
Salt is left behind in the remaining liquid when water evaporates, so Kara must periodically replenish the water that evaporates from the tank to keep the salinity in range.
In considering whether she can leave the tank alone during a week-long business trip, Kara notes that, during her nine-day honeymoon, she left the tank unattended; while its salinity levels did increase, they were still well within the acceptable range when she returned from the trip.
Kara concludes that, as long as the business trip is not extended beyond the planned dates, she can leave the tank unattended during the trip without endangering the fish.
Which of the following, if true, most strengthens the argument above?
(A) Immediately before leaving for her honeymoon, Kara added an unusually large amount of water to the tank, bringing its salinity levels down to their minimum safe levels.
It may be possible that this is the reason why the salinity levels were found bo be within acceptable range when she returned from her honeymoon trip. But she may need to do it every time when she will go for a week-long business trip which may not be possible every time.
Incorrect
(B) In the nine years during which Kara has worked for her current employer, none of her business trips has been extended beyond the planned end date, and she has returned from several of them earlier than planned.
During past 9 years her business trips has never been extended but that is not guaranteed in future. Her weekend long business trips if extended for unforeseen reasons could increase salinity beyond acceptable range. We are assuming best case scenario here which may not be true.
Incorrect
(C) Many of Kara's fish experience significant physiological stress from rapid changes in salinity, such as those that occur when a large amount of water is replenished, even if overall salinity levels remain within the safe range.
This does not strengthens her reasoning since there is an additional factor to be taken into account other than salinity levels which diminishes chances of fish's survival during weekend long business trips. This actually weakens her reasoning by introducing another factor endangering fish.
Incorrect
(D) Since her honeymoon, Kara has moved to a desert region, in which the lack of humidity allows water to evaporate more quickly than in her previous home region.
Since water may evaporate more quickly which may further increase salinity levels more quickly than in her home region, this make the case worse since now the salinity levels may go out of range in less number of days. This means that salinity levels may easily go out of range during her weekend-long business trips. This actually weakens her reasoning.
Incorrect
(E) Since Kara's honeymoon, the walls of her aquarium have developed imperfections in which salt collects and crystallizes, rather than staying dissolved in the remaining water, when water evaporates.
This means that if large volume of water evaporates, then salinity levels may not rise in proportion as salt collects and crystallizes on walls' imperfections and may remain in range for longer periods. This supports her reasoning that she can leave tank unattended for weekend-long business trips without endangering fish.
Correct
IMO E