(2010·江苏)—I prefer shutting myself in and listening to music all day on Sundays.

—That's ________ I don't agree.You should have a more active life.

A．where

B．how

C．when

D．what

小儿染色体病中最常见的一种是_______，母亲______愈大，本病的发生率愈高。