Which of the Following Is(are)essential Characteristics of the Fluidic System

Which of the following is(are) essential characteristics of the fluidic system of a flow cytometer?

A) Adjust the rate of diluent flow depending on cell count (i.e., slower flow for specimens with high counts) .
B) Create a hydrodynamically focused sheath fluid that will cause the cells to flow past the laser in single file.
C) Maintain a slow moving, low pressure solution flow such that there is sufficient time to analyze each cell.
D) All of the above.