Climbing trees for sport

Four students succeeded in climbing to the top of the tree during a tryout in Nanjing University of Science and Technology, which was invited for the national tree-climbing tournament next month. Over twenty students signed up for the competition and only ten went on to the final selection. The competitors are required to climb an eight-meter-tall metasequoia tree, which has quite a straight and smooth surface. Four finally made it to the top in 20-31 seconds.

How tall is the metasequoia tree the students had climbed?

A. eight-meter-tall

B. nigh-meter-tall

C. ten-meter-tall