Hello!

Sorry for the late reply! :(

The IV itself isn't really that important in this question.

What this problem was designed to ask you specifically is

"do you understand what happens to animal cells placed in a hypotonic environment"

which as explained in lecture,

will most likely lead to cells becoming larger as water moves in.

The reason IV is mentioned is to emphase 

1) we are talking about human patients, aka animal cells,

and establish that because we are injecting distilled water directly into the vein,

2) the concentration of the fluid injected will likely result in changes 

to the tonicity of the extracellular fluid in which cells are surrounded in.

anything other than that is way beyond the scope of AP Bio 

so you don't need to worry too much about them.

Good luck studying and let me know if you have any other questions! :D