How is the tāʾ marbūṭah read when stopping on «مُمَدَّدَةٍ»?

Al-Māʿūn and Al-Humazah: Applied Assimilation, Concealment, Madd and Hāʾ Rules

As a doubled nūn
As a sākin hāʾ
As the tanwīn nūn
As an open tāʾ with fatḥah