A sealed discharge tube is observed with a spectroscope. Two bright yellow lines appear at wavelengths of 589.0 nm and 589.6 nm, and no other visible lines are detected. Reference spectra for four elements are listed below.
• Hydrogen (H): 656 nm, 486 nm, 434 nm
• Helium (He): 587.6 nm, 447 nm
• Sodium (Na): 589.0 nm, 589.6 nm
• Neon (Ne): 640 nm, 614 nm, 585 nm
Which element is most likely contained in the discharge tube?
(a) Neon (Ne)
(b) Sodium (Na)
(c) Hydrogen (H)
(d) Helium (He)