Add option on select menu

Not sure if it is possible as there isn’t a place holder present. But is it possible to add “Adults to the first drop down box” and “Children” to the second?

https://cdn.livechat-static.com/api/file/v2/lc/att-old/8801096/842070848fefe98b220669bfb8af86a9/Screenshot%20of%20Grove%20Cottages.jpg