Check the item that CORRECTLY fills in the gaps in the text:

Dogs will eat almost anything—cats, not so much. Here’s why.

     Why are cats such picky eaters when dogs seem willing to wolf down just about anything they encounter? It’s a question many pet parents likely ask themselves while __________ their feline friend to swallow a pill or prying another slobbery piece of mulch from their puppy’s mouth.

      There’s still a lot scientists don’t know about animal taste preferences. But, thanks to a small but growing body of research, researchers are starting to unravel some of the mysteries around our four-legged friends’ flavor fancies. Here’s what we know so far.

       Accidentally drop a cupcake on the ground and your dog will probably scarf it down in one bite. Your cat, on the other hand, may turn up her nose. One possible reason for their ____________ behaviors? Cats can’t taste sweetness.

       Since they couldn’t just ask cats directly, researchers figured this out by analyzing their DNA. House cats, tigers, and cheetahs have a “broken” version of the gene Tas1r2, which works with another gene, Tas1r3, to enable sweetness detection. Though Tas1r3 appears to function perfectly fine in cats, Tas1r2 is an “unexpressed pseudogene” that’s missing 247 letters. Without them, Tas1r2 does not produce a crucial protein needed to form a receptor for sweetness on cats’ taste buds.

       To take the study a step further, they gave 25 felines the choice between a bowl of plain water and one that’d been spiked with molecules that provide umami flavor. As ___________, the cats strongly preferred the umami water, and more specifically, water containing umami compounds present in tuna. That may help explain why felines love the saltwater fish so much.

(Source: National Geographic — adaptation.)