Scotty climbed onto the platform and sat on the stool. without a glance at the audience or a word of introduction, he began to play “i am a little lamb,” a tune whose childishness was belied by the twanging filigree of his slide guitar, its gushy metallic complexity. he followed that with “goats like oats” and “a little tree is just like me.” the amplification was fine and powerful enough to eclipse the chopper throb and deliver the sound even to the distant reaches of the crowd, where it disappeared between buildings. alex listened in a sort of cringe, expecting a roar of rejection from these thousands he’d managed secretly to assemble, whose goodwill had already been taxed by the long wait. but it didn’t happen; the pointers, who already knew these songs, clapped and screeched their approval, and the adults seemed intrigued, attuned to double meanings and hidden layers, which were easy to find.

which of the following choices best describes the structure used in this excerpt?