If those people had used wooden wheels long long time ago then they would have decayed by now and archeologists will not be able to find those wheels. This explains why the evidence is lacking.
I still stick with B.

The recent upheaval in the office-equipment retail business, in which many small firms have gone out of business, has been attributed to the advent of office equipment “superstores” whose high sales volume keeps their prices low. This analysis is flawed, however, since even today the superstores control a very small share of the retail market.

Which of the following, if true, would most weaken the argument that the analysis is flawed?

(A) Most of the larger customers for office equipment purchase under contract directly from manufacturers and thus do not participate in the retail market.
(B) The superstores’ heavy advertising of their low prices has forced prices down throughout the retail market for office supplies.
(C) Some of the superstores that only recently opened have themselves gone out of business.
(D) Most of the office equipment superstores are owned by large retailing chains that also own stores selling other types of goods.
(E) The growing importance of computers in most offices has changed the kind of office equipment retailers must stock.

The argument says that the recent turmoil of retail stores is attributed to superstores. This analysis is flawed because superstores control very small share of retail market. We have to weaken the argument that the analysis is not flawed and show that superstores are somehow responsible for the turmoil of retail stores

Option (B) says that superstores heavy advertising has forced retail stores to bring their prices down which in turn would have resulted in close of retail business.

Archaeologists have found wheeled ceramic toys made by the Toltec, twelfth-century inhabitants of what is now Veracruz. Although there is no archaeological evidence that the Toltec used wheels for anything but toys, some anthropologists hypothesize that wheeled utility vehicles were used to carry materials needed for the monumental structures the Toltec produced.

Which of the following, if true, would most help the anthropologists explain the lack of evidence noted above?

(A) The Toltec sometimes incorporated into their toys representations of utensils or other devices that served some practical purpose.
(B) Any wheeled utility vehicles used by the Toltec could have been made entirely of wood, and unlike ceramic, wood decays rapidly in the humid climate of Veracruz.
(C) Carvings in monument walls suggest that the Toltec's wheeled ceramic toys sometimes had ritual uses in addition to being used by both children and adults as decorations and playthings.
(D) Wheeled utility vehicles were used during the twelfth century in many areas of the world, but during this time wheeled toys were not very common in areas outside Veracruz.
(E) Some of the wheeled ceramic toys were found near the remains of monumental structures.

In the above question we have to show why there is lack of evidence. Option (B) says that wheeled utility vehicles used by Toltec could have been made of wood and wood decays rapidly in the humid climate of veracruz. That is why the evidence is not available.

hi,
what the question is asking us is some reason for lack of evidence for that wheeled utility vehicles were used to carry
materials needed for the monumental structures the Toltec produced....
if we look at the choices...
(A) The Toltec sometimes incorporated into their toys representations of utensils or other devices that served some practical purpose.
it gives a reason to believe in the hypothesize but does not provide any reason for lack of evidence..

(B) Any wheeled utility vehicies used by the Toltec could have been made entirely of wood, and unlike ceramic, wood decays rapidly in the humid climate of Veracruz.
correct ... this gives us the reason we are looking for that is since they were made of wood ,they have decayed and no longer available

(C) Carvings in monument walls suggest that the Toltec’s wheeled ceramic toys sometimes had ritual uses in addition to being used by both children and adults as decorations and playthings.
it just tells us another use but not what we are looking for...

(D) Wheeled utility vehicles were used during the twelfth century in many areas of the world, but during this time wheeled toys were not very common in areas outside Veracruz.
out of scope.. we are not interested in what had happened in other areas as it does not help us in any conclusion...

(E) Some of the wheeled ceramic toys were found near the remains of monumental structures
again out of scope

ans B...
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I chose 'B' by using POE but now after having spent some more time on 'B' I understand why no other option comes even remotely close to it.

The argument says that archaeologists have found wheeled ceramic toys made by the Toltec and they probably could not find any evidence of the fact that the wheels were used for any other purpose except for the toys, anthropologists on the other hand believe that the Toltec used wheeled utility vehicles to carry materials used for the construction of the monuments they produced. We need to find an answer choice that lends some credence to the fact that wheeled utility vehicles were indeed used by the Toltec in the time period specified.
Option 'B' is the correct answer as it says that wheeled utility vehicles were indeed used in those times but the fact that any wheeled vehicle was made from wood and wood decays in the humid climate of that city is the reason why anthropologists are right in their hypothesis and archaeologists could not find any evidence of wheeled utility vehicles as any wheeled vehicles (made of wood) probably produced in the 12th century would have decayed by the time archaeologists surveyed that region in the 21st century.