题目内容：
根据以下材料，回答题The brainis truly a marvel. A seemingly endless library, whose shelves house our mostprecious memories as well as our lifetime's knowledge. But is there a pointwhere it reaches capacity? In other words, can the brain be “full” ?
Theanswer is a resounding no, because, well, brains are more sophisticated thanthat. A study published in Nature Neuroscience earlier this year shows thatinstead of just crowding in, old information is sometimes pushed out of thebrain for new memories to form.
Previousbehavioral studies have shown that learning new information can lead toforgetting.But in this study, researchers used new neuroimaging techniques todemonstrate for the first time how this effect occurs in the brain.
Thepaper's authors set out to investigate what happens in the brain when we try toremember information that's very similar to what we already know. This isimportant because similar information is more likely to interfere with existingknowledge, and it's the stuff that crowds without being useful.
To dothis, they examined how brain activity changes when we try to remember a “target”memory,that is, when we try to recall something very specific, at the same time astrying to remember something similar (a “competing” memory). Participants weretaught to associate a single word (say, the word sand) with two differentimages--such as one of Marilyn Monroe and the other of a hat.
Theyfound that as the target memory was recalled more often, brain activity for itincreased.Meanwhile, brain activity for the competing memory simultaneouslyweakened. This change was most prominent in regions near the front of thebrain, such as the prefrontal cortex, rather than key memory structures in themiddle of the brain, such as the hippocampus, which is traditionally associatedwith memory loss.
Theprefrontal cortex is involved in a range of complex cognitive processes, suchas planning,decision making, and selective retrieval of memory. Extensiveresearch shows this part of the brain works in combination with the hippocampusto retrieve specific memories.
If thehippocampus is the search engine, the prefrontal cortex is the filterdetermining which memory is the most relevant. This suggests that storinginformation alone is not enough for a good memory. The brain also needs to beable to access the relevant information without being distracted by similarcompeting pieces of information.
In dailylife, forgetting actually has clear advantages. Imagine, for instance, that youlost your bank card. The new card you receive will come with a new personalidentification number (PIN).
Researchin this field suggests that each time you remember the new PIN, you graduallyforget the old one: This process improves access to relevant information,without old memories interfering.
When weacquire new information, the brain automatically tries to incorporate it within
existinginformation by forming associations. And when we retrieve information, both thedesired and associated but irrelevant information is recalled.
Themajority of previous research has focused on how we learn and remember new information.But current studies are beginning to place greater emphasis on the conditionsunder which we forget, as its importance begins to be more appreciated.
Which of the following is closest in meaning to the underlined word “resounding”in Paragraph 2? A．Definite.
B．Repetitive.
C．Echoing.
D．Impressive.
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