β⁻ Decay Increases Atomic Number by 1 Steps:

• β⁻ decay transforms a neutron into a proton, emitting an electron and antineutrino.
• Mass number (A) stays the same at 14 for ¹⁴C.
• Atomic number (Z) of carbon is 6; it increases to 7.
• Nuclide with Z=7 and A=14 is nitrogen-14, or ¹⁴N. Why B is correct:
• ¹⁴N has Z=7, matching the result of Z increasing by 1 per the β⁻ decay rule. Why the others are wrong:
• A: ¹⁴C is the original nuclide; decay changes it.
• C: ¹⁴B has Z=5, which would require decreasing Z, opposite of β⁻ decay.
• D: Identical to B, but listed separately—still correct, though B is the intended unique choice.

Final answer: B. ¹⁴N