The observational fact about a cepheid variable star that leads to a measurement of its distance from earth is that its period of variation is directly related to its

absolute brightness

Explanation:

The observational fact about a cepheid variable star that leads to a measurement of its distance from earth is that its period of variation is directly related to its absolute brightness

landlessness of ordinary people

^^something like that^^^

answer they showed that organic molecules such as amino acids could be produced from inoragnic molecules;