The koryu dynasty’s leaders believed that their politics should be guided by the principles of

Confucianism

Explanation:

Even today, Confucianism's ideas have noticeable influences in the Korean society; including their way of life, social relations between older and younger people; moral system; and more. It is considered often as a pragmatic way of keeping unity in the Nation and also, a way of thinking inherited by the Goryeo (or Koryu) dynasty since it was highly supported by the king Seongjong of Goryeo.

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration

c is the correct answer for this question.