Stars q: what is the stellar main sequence? q: what is the energy source of stars on the main sequence? q: what is the main-sequence lifetime of our sun? how does mass affect a star's lifetime on the main sequence?

Which of these is a drawback of using natural gas? a. it is fairly safe for use in homes.b. it burns more cleanly than crude oil products.c. scientists have developed new ways of extracting it.d. during its extraction, groundwater can be contaminated.