What happens after a low-mass star runs out of helium, the core is exposed

Much of the general structure and physical properties of the interior of the earth are inferred from: a)deep oil and gas bore holes b)geologic investigations c)analysis of seismic waves d) study of volcanoes

When you mate two plants together the terms is called? answer it fast as possible plz! i have a test tomorrow!

Apiece of metal with a length of 1.42 cm was measured using four different instruments. which of the following measurements is the most accurate?