Based on what the error says, the key option is missing. In an input_select.select_option action, the data key should contain the key option and the value of the option that is being selected:
action: input_select.select_option
data:
option: THE_OPTION_BEING_SELECTED
target:
entity_id: input_select.example
That being said, error codes are not 100% accurate, so the above is a best guees based on the provided information. In the future, please follow the Community Guidelines by sharing the card configuration. It makes it much easier for us to diagnose the issues.