Read this passage from Through the Looking-Glass.

"I wish I could manage to be glad!” the Queen said. "Only I never can remember the rule. You must be very happy, living in this wood, and being glad whenever you like!”
"Only it is so VERY lonely here!” Alice said in a melancholy voice; and at the thought of her loneliness two large tears came rolling down her cheeks.

Which word in the passage best reveals the meaning of the underlined word?

A. rule
B. glad
C. lonely
D. voice