1. According to an old dictum of fashion, you should never wear what color after Labor Day?

2. Because of an investigation into a bloody murder, the first Sherlock Holmes mystery is titled "A Study in" what?

3. Because its corporate parent, RCA, made color TV sets, NBC chose what animal as its logo in 1956?

4. What kind of fruit did nursery rhyme character Little Jack Horner find in his Christmas pie?

5. Julius Caesar’s troops changed history when they sowed what kind of seeds in the hills around Dijon, France?

What’s the "Kennection" between all five answers?