Which example is a precipitation reaction?
a) solid fe combines with o2 gas to produce solid fe2o3.
b) solid c6h12o6 combines with o2 gas to produce co2 gas and h2o gas.
c) a solution of hci mixes with a solution of naoh to produce a solution of naci.
d) a solution of agno3 mixes with a solution of naci to produce solid agci and a solution of nano3.

The correct answer is option D.                

A solution of AgNO3 mixes with a solution of NaCl to produce solid AgCl and a solution of NaNO3.

AgNO3 + NaCl = AgCl + NaNO3              

Precipitation is a kind of reaction that occur when cations and anions combine together in an aqueous solution and forms a precipitate.

d. groundwater flows through the subsoil and deposits minerals.

i think its white blood cells

i hope this