Cheryl Is in a Lab Attempting to Prepare a Slide

Cheryl is in a lab attempting to prepare a slide of cow blood for observation in a wet mount.She places a small drop of the blood on a slide,adds a drop of strong saline (salt) solution,and then covers all of it with a coverslip.After returning to her desk,she observes the slide with her microscope and notices that all of the red blood cells (RBCs) do not look like the nice round donut-shaped cells in her lab manual.Instead,the RBCs look very shriveled up.Her lab partner,Derek,has also made a slide,but the RBCs on his slide do look like the ones in the lab manual.Derek used a more dilute solution of saline but the same vial of blood. The most plausible explanation for the appearance of the blood cells on Cheryl's slide is that the

A) saline she used was hypotonic to the RBCs; this resulted in water osmosing through the RBC plasma membrane mostly into the cells.
B) saline she used was isotonic to the RBCs; this resulted in water osmosing through the RBC plasma membrane into and out of the cells at an equal rate.
C) saline she used was hypertonic to the RBCs; this resulted in water osmosing through the RBC plasma membrane mostly out of the cell.
D) RBCs were hypertonic to the saline; this resulted in water osmosing through the RBC plasma membrane mostly into the cells.