Question

1. what characteristics of a star are measured and plotted on a simple h-r diagram?

mass and temperature
mass and luminosity
orbit and temperature
luminosity and temperature

Explanation:

The Hertzsprung - Russell (H - R) diagram is a key tool in astronomy (a subfield of Physics, which is under Natural Science) that plots the luminosity (or absolute magnitude) of stars against their temperature (or spectral class). Mass is not a direct axis on a simple H - R diagram, and orbit is not a characteristic plotted on it. So the correct characteristics are luminosity and temperature.

Answer:

The option with "luminosity and temperature" (the last option in the list of radio buttons, as per the text: "luminosity and temperature")