I write professionally though that may be hard to believe on here.
The answer is "is"
Why?
"Range" is an example of a "mass noun."
A noun (such as advice, bread, knowledge, luck, spaghetti, and work) that names things that in English cannot be counted.
A mass noun (also known as a noncount noun) is used only in the singular. Many abstract nouns are uncountable, but not all uncountable nouns are abstract. Contrast with count noun.