Final answer:
Substance B at 343 K would have more kinetic energy compared to substance A at 80 °C.
Step-by-step explanation:
According to the kinetic-molecular theory, the temperature of a substance is proportional to the average kinetic energy of its particles. Therefore, substance B at 343 K would have more kinetic energy compared to substance A at 80 °C. This is because 343 K is a higher temperature than 80 °C, indicating that the particles in substance B are moving at a faster rate and have greater kinetic energy.