To what extent must a given solution of concentration of $40 \, mg$ silver nitrate per $mL$ be diluted to yield a solution of concentration of $16 \, mg$ $AgNO_3$ per $mL$?

• A
  Each $mL$ must be diluted to $2.5 \, mL$
• B
  To each $mL$ of solution $2.5 \, mL$ of water should be added
• C
  To $2.5 \, mL$ of solution $2 \, mL$ of water should be added
• D
  To $1.5 \, mL$ of solution $1.5 \, mL$ of water should be added