Which of the following are good questions to ask when trying to understand a problem? check all that apply. a. does my guess satisfy the equation? b. what is a logical name for the variable? c. how should i present the solution? d. what is the variable? e. is the variable always positive, negative, or either? f. what are the units of the variable?

E) Is the variable always positive, negative , or either.

The second option is correct according to edgenuity

True blindness may be caused by trauma to the eye, severe conjunctivitis due to  ibr (infectious bovine rhinoceros) or pink eye or other infections, leptospirosis, lead poisoning, selenium toxicity, fungal infections, vitamin a  deficiencies, rabies, vitamin b12 deficiency, neoplastic of the orbit or  conjunctiva, cataracts, congenital malformations, etc.