In 2009, the Guinness Book of World Records verified that an English Bulldog named Tillman was the fastest dog on a skateboard, achieving 100 meters in 19.678 seconds. What was Tillman's unit rate in meters per second? (Round to nearest tenth of meter.)
a) 19.7 m/sec
b) 12.5 m/s
c) 5.1 m/sec
d) 4.1 m/s