Which innovation from the song dynasty had the greatest impact on the expansion of global empires?
a. accurate star charts
b. horse stirrups
c. better navigation tools
d. chemistry for explosives.

i think it could be c

The answer is "D. Chemistry for explosives".

Artisans and scholars made essential innovative advances amid the Tang and Song dynasty. Among the most imperative developments were movable type and gunpowder. With movable type, a printer could mastermind squares of individual characters in an edge to make up a page for printing. Beforehand, printers had cut the expressions of an entire page into one substantial square. The development

of gunpowder, in time, prompted the production of explosive weapons, for example, bombs, projectiles, little rockets, and guns.  

Other imperative innovations of this period incorporate porcelain, the mechanical clock, paper cash, and the utilization of the attractive compass for cruising.

d. japan's attack on pearl harbor

frederick william of brandenburg-prussia trained his son, frederick, to be a hardy soldier. but frederick disliked rifle shooting and horseback riding. unlike his father, he was interested in french literature. he enjoyed poetry and music and, like some others of the enlightenment, he scoffed at religion. his father thought him soft, frivolous and unmindful of his duties. and when frederick refused to put his signature on a right to succession, for a few moments his father strangled him.