d.
Because a <em>complete</em> ionic equation wants you to show everything participating in the reaction. Even if some are spectator ions that do not affect the final equation you still must include them and therefore c. could not be the answer.
I got bacteria for this one................
Recycling!! And also planting more trees.
Hope this helps!
Answer: Physical properties of matter include color, hardness, malleability, solubility, electrical conductivity, density, melting point, and boiling point. For the elements, color does not vary much from one element to the next
