Answer: the third option, the attraction between particles causes a gas to condense at low temperatures
Step-by-step explanation:
1) The kinetic-molecular theory explains the behaviour and properties of the gases in terms of the energy, size, and motion of its particles or molecules.
2) As per the size, the particles are considered to make a small portion of the total volume of the gas, to the point that their size is fully neglected (zero). The particles are considered to not occupy any space (volume) of the gas.
3) The first and the second statments are directly stated by the molecular-kinetic theory: a) the average kinetic energy of particles depends only on the temperature, and b) the particles in a gas travel in straight lines in a continuous, random motion.
Regarding the statement that the attraction between particles causes a gas to condense at low temperatures, this is not true.
First of all, the kinetic molecular theory of the gases is not valid at low temperatures and hight pressures.
Second, depending on the gas and the intermolecular force, at low temperarures a gas might condense or not. It depends on the attractive forces, which are neglected for gases by the molecular-kinetic theory.