Which famous dog was a WWI fighter ace in the signal corps?

The correct answer is Snoopy, the beloved beagle from Charles Schulz's comic strip "Peanuts." Snoopy is famously known for his imaginative portrayal as a World War I flying ace, often depicted wearing a pilot's scarf and flying a doghouse as his Sopwith Camel aircraft. This character serves as a whimsical nod to the bravery and heroism associated with fighter pilots in WWI.

While the other choices may represent notable dogs in popular culture or movies, none have the specific historical tie to the WWI fighter ace theme that Snoopy embodies. Rin Tin Tin, for instance, is also a famous canine icon but is primarily known for his film roles and contributions to the war effort through entertainment rather than direct military involvement as characterized by Snoopy's fictional adventures.