Suppose a daredevil with a mass of 70 kg jumps off a one-story building with a homemade 10 kg jetpack attached to their body. (This is just a test flight!) The jetpack is able to provide 350 N of upward thrust. Assuming the jetpack always points straight down (so that its thrust is always upward), what is the downward acceleration of the daredevil?

a) 4.9 m/s²

b) 3.3 m/s²

c) 2.4 m/s²

d) 1.8 m/s²