A car increase velocity from 30 m/s to 60 m/s in 4 seconds

The slope of a good speed time indicates ? a. velocity b. acceleration c. direction d. speed

May someone explain how to do this question?

Which lists the fundamental forces in order, from strongest to weakest? strong nuclear, weak nuclear, electromagnetic, gravitational strong nuclear, electromagnetic, weak nuclear, gravitational gravitational, weak nuclear, electromagnetic, strong nuclear electromagnetic, gravitational, strong nuclear, weak nuclear