Option 1 states that the desirable range of pH for drinking water is 6.5 to 8.5. pH is a measure of how acidic or alkaline a substance is, on a scale of 0 to 14, with 7 being neutral. A pH value below 7 indicates acidity, while a pH value above 7 indicates alkalinity.

In the case of drinking water, a slightly alkaline pH is generally considered preferable as it helps to neutralize acidity in the body and maintain a healthy pH balance. The range of 6.5 to 8.5 provided in option 1 falls within this slightly alkaline range.

Option 2 suggests a range of 5.0 to 6.5, which is more acidic than the desirable range for drinking water. Option 3 suggests a range of 6.5 to 7.0, which is at the lower end of the desirable range but still within the acceptable range. Option 4 suggests a range of 7.0 to 8.5, which is within the desirable range stated in option 1.

In conclusion, option 1 accurately states that the desirable range of pH for drinking water is 6.5 to 8.5.