PrepTest 103, Section 1, Question 19
Sponges attach to the ocean floor, continually filtering(67 more words not shown)
The statements above, if true,(9 more words not shown)
- AFew tubular or(8 more words not shown)
- BTubular and vase-shaped(14 more words not shown)
- CDuring the late(14 more words not shown)
- DAll sponges that(17 more words not shown)
- ENo types of(23 more words not shown)
Reading the argument
Where would these sponges have lived if strong currents had been everywhere?
Their shape matters in two ways. They can eject filtered water without a current helping them, so quiet water works for them. But strong currents would pull them off the ocean floor, so those currents rule out a place to live. This is more than a preference for calmer conditions: the sponges can't live in the strong currents described.
What we’re looking for
Both kinds were widespread during the late Jurassic period. Put that together with their needs, and there must have been many suitable places for them—areas with weak currents. That's my prediction for the most-supported answer. Their widespread presence tells us something about the conditions that allowed them to live.
Working the answers
- A
We know they were widespread during the late Jurassic period, but we aren't told when they first appeared or how common they were beforehand. They could also have been widespread earlier. A turns information about one period into an unsupported comparison with another.
- B
The same problem applies to later periods. Being widespread at one time doesn't mean being more common then than afterward. These sponges might have remained equally common or become even more common. We have no later population information.
- CCorrect
These sponges needed places without the strong currents that would dislodge them. If both types were widespread, suitable weak-current areas must have existed in many places. C connects the sponges' requirements with the period in which they were widespread.
- D
We haven't been told that every other sponge lives in extremely strong currents. Some could live in quiet water too; others could live in moderately moving water. A restriction on these two shapes doesn't give every other shape the opposite requirement. “All” and “extremely strong” add claims the passage doesn't support.
- E
Avoiding water a sponge has just filtered doesn't establish that no sponges live in large colonies. The passage doesn't tell us how closely they live together or whether water movement and other conditions make colonies possible. E adds a universal claim about their living arrangements that we cannot derive from the stated feeding behavior.
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