Explanation
According to the Snowflake documentation1, the SECURITYADMIN role is responsible for managing all grants on objects in the account, including system grants. The USERADMIN role can only create and manage users and roles, but not grant privileges on other objects. Therefore, the function that is unique to the SECURITYADMIN role is to manage system grants. Option A is incorrect because both roles can reset a user's password. Option C is incorrect because both roles can create new users. Option D is incorrect because both roles can create new roles.