Which of the following is the correct sequence in the life cycle of a low-mass star?
a. protostar, main sequence star, red giant, planetary nebula, white dwarf

b. planetary nebula, red giant, white dwarf, main sequence star black hole

c. white dwarf, red giant, main sequence star, red supergiant, black hole

d. protostar, main sequence star, red giant, red supergiant, supernova

The correct answer is A. Protostar, main sequence star, red giant, planetary nebulosa, white dwarf.

Explanation

In astronomy, a low mass star is a term used to refer to a star that has a mass below ~ 0.6 solar masses. The life cycle of these stars consists of five stages; the first is the protostar, at this stage the star is just a gravitational collapse of different elements that form molecular clouds, which is compressed by expelling energy and gradually heating its nucleus; the second stage is the main sequence of the star, in which by means of the fusion of hydrogen atoms subjected to high temperatures, helium atoms are produced; the third stage is the red giant, in it all the hydrogen has been transformed into helium, this causes the atmosphere of the star to expand until that helium is converted to carbon; the fourth stage is the planetary nebula, in which some outer layers of the star move away from its nucleus forming clouds that are diluted in space, at the same time its nucleus continues to emit heat and light due to the high temperature it has; finally, in the fifth stage that nucleus decreases its size and turns white that informs the death of the star. So, the correct answer is A.protostar, main sequence star, red giant, planetary nebula, white dwarf.

relationships aren't everything. people everyday spend there entire life depending on reltionships and for someone to be there for them when this is absurd. why must people depend on someone else to bring them happiness? i'm not saying it wrong to feel happy with someone, but people feel that they need to be in a relationship in order to feel happy, when, this is not true. you can paint, write, read ir slend tume with family ir even spend time working in yourself. this can be an exciting experience to find yourself. it's bot wrong to be in a relationship but if you let it be your only source of happiness, than you will never find true happiness.

so, relationships are not always worth it. if you are so dependent on them, than in the end they arent worth it because you will realize how unhappy you really were. some people even tend to cut ties with family because they think they cabt make them happy, obly realtionships with a lover can. false. in order to find true happiness, one must learn to love themselves if they want to love someone else. it's unhealthy to be always depend on relationships and to alqays be in and out of one.

so live life, get that job you always wanted, buy those new shoes and love yourself. depend on yourself, not others. they arent worth it, you can make yourself more happier than most people can do to you. it's not woth it. take your time and have fun.

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.