D. Reaction time
Objects falling are moving quickly, and being able to react immediately is the most useful skill in this situation. Being agile or having good balance isn't helpful if the object has reached the ground before you moved.
A helmet is the best!! So C!
To prevent a child from touching or sticking anything inside a plug-in, I would use guards to cover the holes. Smaller children have a difficult time trying to remove the guards, which gives enough time to notice him/her messing with the plug. Serious injuries, even death, can occur when being electrocuted. It is very important to prevent any small objects from being pushed into the sockets.
National parks reduce the human impact on land by preventing human development.
