I think the correct answer would be the first option. The best method to use in order to measure the distance of star would be to calculate the variations in the position of the star due to movement of Earth in its orbit. The doppler shift which is what is being described in the last three options does not calculate the distance rather it calculates the relative velocity. The method used in measuring the distance was introduced by Edwin Hubble where he found that relative velocity of a body in space is directly proportional to the distance of that body from Earth.
Toxins are microbial proteins with a strong specificity for a target cell that exert extremely powerful and toxic effects on that cell.
<h3>What are toxins?</h3>
Toxins are molecules that are produced by certain organisms which are deadly to other organisms when these organisms come in contact with them.
Toxins are produces mostly by microorganisms as well as some plants and animals such as fishes.
Toxins are mostly proteins products are usually specific for their targets cells.
Therefore, microbial proteins with a strong specificity for a target cell that exert extremely powerful, and sometimes deadly, effects on that cell are called toxins.
Learn more about toxins at: brainly.com/question/1235358
The answer would be the first one
