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