A scientist is observing a distant star that is moving toward the Earth at a relative speed of 300 km/s. The star emits light at a wavelength of 500 nm, which is characteristic of a particular element in the star's atmosphere. (i) What is the shift in wavelength of the 500-nm light as observed from Earth? (ii) Is this a redshift or a blueshift? (iii) If the star is currently 4.0 million light-years away, how long will it take for the star to collide with Earth, ignoring the expansion of the universe?

• A. (i) - 0.20 nm (ii) redshift (iii) 600 billion years
• B. (i) - 0.20 nm (ii) redshift (iii) 4.0 billion years
• C. (i) - 0.50 nm (ii) blueshift (iii) 600 billion years
• D. (i) - 0.50 nm (ii) blueshift (iii) 4.0 billion years