Question

protect means:
whirl
defend
separate
terrify

Explanation:

"Protect" means to keep someone or something safe from harm. "Defend" also means to protect someone or something from attack or harm. "Whirl" means to move or cause to move rapidly around and around. "Separate" means to divide or keep apart. "Terrify" means to fill someone with extreme fear. So, "defend" is the synonym of "protect".

Answer:

defend