What's a grenade?

Although the city wall was only a five-minute walk from where Luke's group previously was, it took them over an hour because Julia, Rio, Lori, Professor Nina, and Ben took quite a bit of time to kill zombies.

Luke, Alice, and Shadow only joined the battle when they were outnumbered by a lot, were on the verge of getting injured or dying, or encountered zombies stronger than level 5.

Thanks to this, Ben, Lori, and Rio had reached levels 6, 5, and 6, respectively, and were no longer prone to zombie infection, which meant Luke and others no longer had to worry about them as much.

As for Julia and Professor Nina, they had reached levels 3 and 4, respectively, had gained quite a bit of fighting experience, and their fear of zombies had decreased significantly.

Seeing them become evolvers, Rio's wife also tried to kill a zombie but fainted when it appeared right in front of her. So, now only she and Kean were the ones who needed protection.