The first sentence describes what researchers suspected. The second part describes what recent experiments show. Think about whether these two ideas match or differ.

Mentally swap in each option and see if the sentence makes logical sense: does it show a result, give an example, show something happening at the same time, or signal a change from the earlier idea?

Read the first sentence: "Researchers have long suspected that honeybees navigate using landmarks around the hive." This tells us what scientists previously believed about bee navigation: they thought bees used nearby landmarks.

Now read the part after the blank: "recent experiments show that bees released in unfamiliar territory can still find their way home by reading patterns in the sky’s polarized light." This presents new experimental evidence that bees can navigate in an unfamiliar place using patterns in the sky, not just nearby landmarks.

Compare the old belief with the new result. The old belief focuses on local landmarks; the new result shows bees can navigate even without familiar landmarks, using a different method. That means the second idea does not support or give an example of the first; instead, it challenges or contrasts with it.

Now match that relationship to the answer choices: we need a transition that signals a contrast between earlier suspicion and new, conflicting evidence. Among the options, “However,” is the transition that shows this kind of contrast, so D) However, is the correct answer.