vasuca10 wrote:
VeritasPrepHailey mam Please guide for this question... I was stuck in two answer choices A and D and eventually marked incorrect answer choice D
Conclusion that needs to be strengthened is to use ECC instead of standard concrete as 1) It prevents ice buildup during winters 2) Cost of Electricity needed is less than cost of deicing salt
What I thought was Option D is strengthening our conclusion by advocating why ECC is effective for usage
Kindly explain process of elimination for all Options mam so that I can know where is the mistake in my thought process
Sure thing, vasuca10! Highway Official: When resurfacing our concrete bridges, we should use electrically conductive concrete (ECC) rather than standard concrete. In the winter, ECC can be heated by passing an electric current through it, thereby preventing ice buildup. The cost of the electricity needed is substantially lower than the cost of the de-icing salt we currently use.
Taxpayer: But construction costs for ECC are much higher than for standard concrete, so your proposal is probably not justifiable on economic grounds.
Which of the following, if true, could best be used to support the highway official’s proposal in the face of taxpayer’s objection?
So, we're looking to address why the choice to use ECC rather than standard concrete would be justifiable on economic grounds, despite the fact that construction costs are higher than for standard concrete.(A) The use of de-icing salt causes corrosion of the reinforcing steel in concrete bridge decks and damage to the concrete itself, thereby considerably shortening the useful life of concrete bridges.
<- If de-icing salt lessens the useful life of concrete structures, this provides an excellent reason why ECC might make more economic sense, despite the higher construction costs. If ECC lasts longer and costs less to maintain temperature control - it could make economic sense despite the higher construction costs! We have our answer!
(B) Severe icing conditions can cause power outages and slow down the work of emergency crews trying to get power restored.
<- Pretty irrelevant to us here, as both perspectives in our argument are addressing options for building/maintaining safe roadways, not whether or not we need de-icing options at all!(C) In weather conditions conducive to icing, ice generally forms on the concrete surfaces of bridges well before it forms on parts of the roadway that go over solid ground.
<- Again, this doesn't address the potential net difference in cost between regular concrete + de-icing vs. ECC.(D) Aside from its potential use for de-icing bridges, ECC might also be an effective means of keeping other concrete structures such as parking garages and airport runways ice free.
<- Effectiveness isn't what we're addressing in this argument. The taxpayer is claiming that construction costs (regardless of whether this concrete structure is built for planes, trains, or automobiles!) make ECC a less economically viable option. We need something that tells us ECC is in fact economically viable/wise, despite these construction costs, and (D) fails to address this. (E) If ECC were to be used for a bridge surface, the electric current would be turned on only at times at which ice was likely to form.
<- We only use the current when needed, we only de-ice when needed... again, this doesn't bring a new piece of evidence into the mix that addresses why ECC is economically viable despite its higher construction costs.
So, we want to be sure we're addressing the argument and conclusion presented to us. (That seems to be where you got caught up here.) Here, we aren't just trying to address why ECC is "good" or "effective," we want something that specifically counters the taxpayer's argument and addresses why it is economically justified as compared to the use of traditional concrete. Only (A) accomplishes this goal.