Which is the active third-person masculine plural under lam?

Negating the Imperfect with Lan and Lam: Subjunctive, Jussive and Full Paradigms

• لَمْ يَفْعَلُوا
• لَمْ يُفْعَلُوا
• لَمْ تَفْعَلُوا
• لَمْ يَفْعَلُونَ