45
(A)whether
(B)where
(C)when
(D)why

 Their limbs twitch, they breathe more rapidly, and colors flash across their skin. Scientists aren't sure _____ octopuses dream. Some suggest it might help them improve their camouflage techniques, and others think it could enable them to review and learn from past experiences. Perhaps one day, scientists will be able to fully understand these complex creatures.

牠們的四肢會抽動，呼吸會變得更快，皮膚上還會閃現出各種顏色。科學家們不確定章魚______會做夢。有些人認為這可能幫助牠們改善偽裝技巧，而另一些人則認為這可能讓牠們能回顧並從過去的經驗中學習。也許有一天，科學家將能完全了解這些複雜的生物。