Which word in this passage from "Let George Do It!" helps you to understand that the boys thought the river was exciting? "The sun sparkled tantalizingly on the waters of the Columbia River. The river always held a special lure for these adventuresome boys. The exuberance of youth filled George - his father's request was forgotten. George cupped his hands and yelled, "Here I come, wait." Running, he kicked at the sagebrush that would defy his advance."

tantalizingly
defy
adventuresome
exuberance