Select the correct option regarding the method of separating two sulfide ores by the froth flotation process.
$(1)$ The ratio of water and oil is chosen appropriately.
$(2)$ Some depressants are used for this process.
$(3)$ $HCN$ is a depressant for a mixture of $ZnS$ and $PbS$.
$(4)$ By using a suitable depressant for a mixture of $ZnS$ and $PbS$,only $PbS$ comes up with the froth.

• A
  $T, T, T, F$
• B
  $T, T, T, T$
• C
  $F, F, T, T$
• D
  $T, T, F, F$