Final answer:
Elaine's rights as a common-law partner upon separation from Mellie could include seeking spousal support if she was financially dependent on Mellie's income.
Step-by-step explanation:
In the scenario you have described, Elaine has been in a common-law partnership with Mellie for 15 years and has contributed to the household expenses including the mortgage. The rights Elaine may have upon separation can vary significantly depending on the jurisdiction they reside in. Generally speaking, common-law partners are not granted all the same rights as married couples in terms of property division (option a), unless there are specific statutes or legal principles in place in their jurisdiction that provide for such rights.
Option c, Elaine can seek spousal support, is likely the most accurate. If Elaine has been dependent on Mellie's income, she might have the right to seek spousal support to maintain a standard of living similar to what she had during the relationship. As for option d, Elaine's contribution to the mortgage and household bills does not automatically entitle her to property division; this would depend on local laws governing common-law relationships and property rights.