How to retrieve customfieldoptions for a custom field


we are integrating JIRA with one of our custom application, where from the application we need to create a Issue using JIRA API (using c#), while creating the issue we have several custom fields with multi select options, using the field metadata iam able to retrieve the custom field id (customfield_xxxxx) but for this custom field iam not able to retrieve all the available options, is there any way using this custom field id i can get the available options.
When i search online i got he below url using which i can get the value custom field option but i need to pass the id at the end, can any one please suggest how to get this id or is there any other alternative i can use to get the values.

Dear @RaejshKumar,

you can do what you want, but you need to know the project. There is no standard REST call that returns all options of one custom field.

First get all issue types of one project, where you want to create an issue:

GET /rest/api/2/issue/createmeta/{projectIdOrKey}/issuetypes

From the response select the issue type you want to use and then pull the metadata for exactly this issue type with:

GET /rest/api/2/issue/createmeta/{projectIdOrKey}/issuetypes/{issueTypeId}

In the JSON response all option are listed.

Alternatively you can search the marketplace for plugins that can return custom field options with REST.

So long