$\mathrm{CaC}_2$ and $\mathrm{H}_2 \mathrm{O}$ react to produce

• A

  $\mathrm{CH}_4$
• B

  $\mathrm{C}_2 \mathrm{H}_4$
• Correct answer
  C

  $\mathrm{C}_2 \mathrm{H}_2$
• D

  $\mathrm{C}_2 \mathrm{H}_6$

Hence, the correct answer is option: 'C'.