Which example contains a concealed subject?

Rules of the Fāʿil: Explicit Nouns, Pronouns, Number and Gender

• ذَهَبَ زَيْدٌ
• ضَرَبَ زَيْدٌ عَمْرًا
• زَيْدٌ ذَهَبَ
• الزَّيْدَانِ