What is the city code for Redding, California?

The city code for Redding, California, is RDD. City codes are standardized three-letter codes used by airlines and travel organizations to simplify the identification of airports. Each code is unique to a specific airport or location.

In this case, RDD specifically corresponds to Redding Municipal Airport, which serves the city of Redding. This association makes it the correct choice for identifying the location in question. The other choices represent codes for different cities or airports: HNL is for Honolulu, SLC is for Salt Lake City, and ORD is for Chicago O'Hare. Each of these codes refers to locations that are not related to Redding, reinforcing the accuracy of RDD as the correct answer.