What groovy item was invented by Englishman Edward Craven Walker in 1963?

A: Leisure suit

B: Lava lamp

C: Eight-track tape deck

D: Hot comb

Explanation: Groovy, baby! Lava lamps, which were a fixture in every hip pad in the 1960s and 70s, featured a mixture of water and colored oil that created swirl patterns when heated by a light bulb.