Lee and Leigh are twins. At their first birthday party, Lee is placed on a spaceship that travels away from the earth and back at a steady \(0.866 \mathrm{c}\). The spaceship eventually returns, landing in the swimming pool at Leigh's eleventh birthday party. When Lee emerges from the ship, it is discovered that

A. He is still only 1 year old.

B. He is 6 years old.

C. He is also 11 years old.

D. He is 21 years old.