Read the passage carefully and choose the correct answer.

50 years back in time and even before that, in the absence of the Internet and various hi-tech toys, the entertainment world used to be so different from what it is nowadays. Running wild on the pastures, and bathing in the river, children back then saw nature as their playground and were curious to explore and enjoy it in their own creative ways. They found small objects around them to make toys. Boys used branches as swords for mock battles while girls used them as chopsticks to play imaginary restaurants. In this way, children enjoyed themselves on the way to school, during school breaks, and even when they were herding buffaloes. At that time, tug of war, hide and seek, and skipping were popular games. Some have even made it through to today.

The fact that those popular games which were meant to be played in groups made it easier and faster for children to make friends. Moreover, people rarely moved away from their hometown, so childhood bonds were even stronger as children grew up playing together all their life.More than 35,000 staff and volunteers with the Red Cross Society of China responded to the disaster by distributing food, water, tents and other essential items. The International Federation of Red Cross and Red Crescent Societies are providing 100,000 tents to help those in need.

The word “explore” could be replaced by ..............