Read this excerpt from "are dogs dumb? " by karen hopkin.

norton milgram and his coworkers at the university of toronto at scarborough use treats to give dogs a canine iq test. the dog is presented with a tray with a blue block on it; underneath the block is a treat. the animal moves the block and gets the treat. so far, so good. now the test gets tricky. the dog is presented with the same tray, but this time it has both a blue block and a yellow coffee can lid (or white bowl or black square of cloth) on it; the treat is now under the yellow lid (or white bowl, the test: how long does it take for the dog to learn that the treat is always under the new item on the tray? the smarter the dog, the quicker she'll find the treat.

which detail from the text best supports the inference that dogs are smart?

a. the dog is presented with a tray with a blue block on it; underneath the block is a treat.

b. norton milgram and his coworkers at the university of toronto at scarborough use treats to give dogs a canine iq test.

c. …how long does it take for the dog to learn that the treat is always under the new item on the tray?

d. the dog is presented with the same tray, but this time it has both a blue block and a yellow coffee can lid…

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