A water sample from a municipal water supply was found to have a pH = 7.0. On evaporating 2 L of this water, 2.016 g of white solid was left behind in the evaporation vessel, so the total dissolved solid (TDS) content of this water was $$1008 \text{ mg L}^{-1}$$. However, addition of soap to a bucket of this water did not produce any visible scum. Based on these findings, one can conclude that

A

there are no $$\text{Ca}^{2+}$$ or $$\text{Mg}^{2+}$$ ion in the water

B

there are no $$\text{CO}_3^{2-}$$ or $$\text{HCO}_3^-$$ ion in the water

C

concentration of any ion in the water is lower than 0.038 M

D

water may be containing $$\text{Na}^+$$ ions in concentration $$ > 0.04 $$ M