We will discard options that don't fit the situation:
Option b: <em>Incorrect </em>since if the driver "hits the gas" then velocity is augmenting and it's not constant.
Option c and d: <em>Incorrect </em>since the situation doesn't give us any information that could be related directly to the terrain or movement direction.
Option a: Correct. At <em>stage 1</em> we can assume the driver was going at constant speed which means acceleration is constantly zero. At <em>stage 2 </em>we can assume the driver augmented speed linearly, this is, with constant positive acceleration. At <em>stage 3 </em>we can assume the driver slowed the speed linearly, with constant negative acceleration.
The model of the atom that is missing from the set is the Thomson’s model. J. J. Thomson portrayed his atom model to look like a plum pudding. In his model, he described that an atom is composed mainly of electrons.
