The correct option is
E explain adequately how people, unlike computers, are able to understand meaning
The author's attitude toward Searle's argument is apparent in the first paragraph, which ends with the author's summary of what Searle is saying. Computers understand structures, Searle argues, but only people understand meaning. How do people understand meaning? The author notes that Searle is not able to answer this question and is able only to assert that people have causal powers of the brain.
A The author makes it clear in the first paragraph that Searle does distinguish between the two. In Searle's view computers are syntactic, interpreting structure or arrangement, rather than semantic, understanding meaning.
B Correct. The first paragraph ends with the contrast between people and computers: People, on the other hand, understand meaning because they have something Searle obscurely calls the causal powers of the brain. By calling Searle's explanation obscure, the author implies that Searle has not adequately clarified how people understand meaning.
C Nothing in the passage criticizes Searle for not providing concrete examples. Indeed, in the second paragraph, the author anticipates how Searle would react to one concrete example, the computer simulation of the stomach.
D In the first paragraph, the author says that Searle argues that computers simply follow algorithms; whether or not Searle understands how they use algorithms is irrelevant.
E Since, as the author suggests in the first paragraph, Searle does not believe information could be a code transmitted from neuron to neuron, he cannot be expected to decipher that code.
The correct answer is B.