Which statement about the star life cycle is true?

Which statement about the star life cycle is true?

• A. Nebula is formed from a star
• B. The sequence Nebula -> Big Star -> Red Supergiant -> Supernova is a path
• C. The Sun is primarily made of helium
• D. A comet is primarily rock

Answer: (B)

Stars begin life in a nebula, a cloud of gas and dust, where gravity pulls material together to form a new star. For very massive stars, after they spend time as a big, bright main-sequence star, they expand into a red supergiant and eventually explode in a supernova. So the sequence nebula → big star → red supergiant → supernova describes a realistic path for the fate of massive stars, making it true. Other statements don’t fit: nebulae are the birthplaces of stars, not something formed from a star; the Sun is mainly hydrogen, not helium; and comets are icy bodies with rock and dust, not primarily rock.

Stars begin life in a nebula, a cloud of gas and dust, where gravity pulls material together to form a new star. For very massive stars, after they spend time as a big, bright main-sequence star, they expand into a red supergiant and eventually explode in a supernova. So the sequence nebula → big star → red supergiant → supernova describes a realistic path for the fate of massive stars, making it true.

Other statements don’t fit: nebulae are the birthplaces of stars, not something formed from a star; the Sun is mainly hydrogen, not helium; and comets are icy bodies with rock and dust, not primarily rock.