Investments are typically evaluated on what is termed a "risk$/$reward$"$ ratio $($i$.$e$.,$ how much "risk" or variability is associated with an expected "reward" or return$).$ On this basis, which of the following statements is most correct or most representative as it concerns how to mathematically express this concept?

HINT: Read this very, very carefully. Remember that mathematical expressions need to be ACCURATE.

Question options:

Question $3$ options:

$1.$Expected Return minus Standard Deviation.

$2.$

Expected Return divided by Standard Deviation.

$3.$

Standard Deviation times Expected Return.

$4.$

Standard Deviation divided by Expected Return.