If the extracellular fluid has an excess of sodium ions, a. sodium ions move into cells b. intracellular fluid moves to the outside of cells c. phosphate and calcium ions are eliminated in feces d. blood levels of arsenic and oxalate increase

b. intracellular fluid moves to the outside of cells

Explanation:

The presence of an excess of sodium ions in the extracellular fluid would make it hypertonic with respect to the intracellular fluid. The concentration gradient would drive the intracellular fluid towards the outside of the cell to balance the concentration of the fluids on either side. The passive movement of fluids occurs across the cells and is driven by the concentration gradient only. The biological membranes are permeable for fluid movement such as the movement of water across it.