Let's begin by breaking down the passage. The first sentence is the conclusion, and the second sentence is a supporting premise. Therefore, the main conclusion is that "research into artificial intelligence will fail to produce truly intelligent machines unless the focus of the discipline is radically changed." We should remember that the word "unless" is a Sufficient/Necessary indicator. We can convert this statement into simpler "if/then" language if we make the part of the sentence following the word "unless" into the necessary condition and negate the other part of the sentence and make it into the sufficient condition.
This gives us: (If) research into AI will produce truly intelligent machines -> (then) the focus of the disciple is radically changed The contrapositive is: (If) the focus of the disciple is not radically changed -> (then) research into AI will fail to produce truly intelligent machines
Answer choice (B) states: "If the current focus of research into artificial intelligence is not radically changed, this research will not be able to produce machines capable of true intelligence." This is a restatement of the contrapositive that we identified above, so it is a correct characterization of the main conclusion.
Does that make sense? Please let us know if you have any other questions!