Final answer:
The United States is the nation that has not ratified the UN Convention on the Rights of the Child as of 2015.
Step-by-step explanation:
The nation that has not ratified the UN Convention on the Rights of the Child as of 2015 is the United States. Although the United States has generally been a supporter of human rights, it has not ratified this particular convention. The convention aims to protect the rights and well-being of children worldwide, including the right to education, health, and protection against exploitation.The United Nations, since its formation in 1945 and the subsequent adoption of the Universal Declaration of Human Rights (UDHR), has been vital in promoting human rights and child protection standards. The goals of the UN include maintaining international peace, promoting sustainable development, and delivering humanitarian aid. These objectives underscore the global effort to eradicate child labor and protect children's rights as part of the Sustainable Development Goals, which have a target to eliminate child labor by 2025.