Which heavy-nūn form means “the two women will certainly do”?

Emphatic Lām and the Heavy and Light Nūn Paradigms

• لَيَفْعَلُنَّ
• لَتَفْعَلَانِّ
• لَيَفْعَلْنَانِّ
• لَتَفْعَلِنَّ