The preconditions for declines in this variable were memorably summarized by Ansley Coale in the dictum “ready, willing, and able.” In Gregory Clark’s Malthusian (10[1])model, an upwards-sloping curve representing this variable appears on the top of two graphs. This variable can fall when quality dominates quantity (10[1])in a trade-off introduced by Gary Becker. A fall in this variable (-5[2])made France the first country (10[1])to undergo a historical (10[2])“transition” (10[2])that (10[1])universally (10[2])accompanies (10[1])economic development. (10[6]-5[2])When this (-5[1])variable (10[1])is low, an “inverted pyramid” (10[5])shape (10[4])is generated (10[1]-5[1])on a common (10[3])plot (10[1])that shows age on the y-axis. (10[1])South (10[1])Korea falls far below the “replacement (-5[1])rate” of this variable at around 2.1. For 10 points, name this variable that was sharply reduced by China’s one-child (10[1])policy. (10[1])■END■ (10[6])