The correct option is (b).
Explanation
The Paris Agreement is a legally binding international treaty on climate change adopted by 196 Parties at the 21st Conference of the Parties (COP 21) to the United Nations Framework Convention on Climate Change (UNFCCC) in December 2015.
Statement 1 is Incorrect: The Agreement was not signed by all UN member countries immediately, nor did it go into effect in 2017. It entered into force on November 4, 2016, thirty days after the date on which at least 55 Parties to the Convention accounting in total for at least an estimated 55% of the total global greenhouse gas emissions had deposited their instruments of ratification.
Statement 2 is Correct: Article 2 of the Paris Agreement explicitly sets the goal of holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.
Statement 3 is Incorrect: The financial commitment reaffirmed during the Paris talks was for developed countries to mobilize $100 billion per year by 2020 to address the needs of developing countries. The statement incorrectly exaggerates this figure to $1000 billion.
Key Takeaway: The Paris Agreement targets a temperature rise limit of well below 2°C (aiming for 1.5°C) and reaffirms the climate finance goal of $100 billion annually from developed to developing nations.