Which of the following statements is false?

• A

  $\mathrm{M}{\mathrm{g}}^{2+}$ ions form a complex with ATP.
• B

  $\mathrm{C}{\mathrm{a}}^{2+}$ ions are important in blood clotting.
• Correct answer
  C

  $\mathrm{C}{\mathrm{a}}^{2+}$ ions are not important in maintaining the regular beating of the heart.
• D

  $\mathrm{M}{\mathrm{g}}^{2+}$ ions are important in the green parts of plants.

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