Step 1: Understanding the Earth Summit
The first International Earth Summit is officially known as the United Nations Conference on Environment and Development (UNCED). It was a major United Nations conference held in 1992 to discuss global environmental and sustainable development issues.
Step 2: Venue of the summit
The conference was held in Rio de Janeiro, Brazil, from 3rd to 14th June, 1992. Hence, it is also called the Rio Summit.
Step 3: Significance
At the Rio Summit, important agreements like Agenda 21, the Convention on Biological Diversity, and the Framework Convention on Climate Change (UNFCCC) were signed.
Step 4: Conclusion
Thus, the correct answer is:
\[
\boxed{\text{Rio De Janeiro, Brazil}}
\]
The value of $\dfrac{1+\cot^2 \theta}{1+\tan^2 \theta}$ will be: