GMAT Test Prep: DS-61495247 GMAT Data Sufficiency

In the number 0.58d6 what number does the digit d represent?

(1) If the number 0.58d6 were rounded to the nearest hundredth the result would be 0.59

(2) If the number 0.58d6 were rounded to the nearest thousandth the result would be 0.586.
Select one of the following answer choices