A student must time a pendulum that swings once in about 2.00 s. To keep the percentage uncertainty in the measured time below 0.25 %, which stopwatch should be chosen?
a) Hand-held stopwatch, least count 0.01s
b) Digital stopwatch, least count 0.001s
c) Stop-watch app, least count 0.05s
d) Analogue lab stopwatch, least count 0.02s