Options: a). You can even use a lock ring to lock your window. Make sure to lock the windows if they will be moving around in windows. b). If you have a power panel on your windows that will be installed later, you can lock it now. Install a windows-only unit to ensure baby protection. c). If your windows do not have keys, however, use another method. Installing keys is costly and time-consuming and it's far easier to use an alternative window locking method. d). If your windows do not have locks, you do not need to lock them. If the windows have not a lock feature, they can be unlocked with a key.Choose from options above and answer: What most naturally follows?

How to babyproof windows
Lock your windows.
Many windows have built-in locks you can latch shut with a key to prevent the window from opening. If your windows have keys built-in, this is your best option for baby proofing your windows.
Answer:
c).