<prompt> True about struma ovarii -a Ectopic thyroid tissueb Ectopic ovarian tissuec It is benignd It is included in teratomaabcadbcacd  <response>: Struma ovarii is the presence of mature thyroid tissue as a major cellular component in an ovarian tumor.Ovarian tumor is nearly always a teratoma.Most of the tumors are benign and in some cases thyrotoxicosis develops. 