Select the most appropriate synonym of the highlighted word.
The outcome document of the Rio+20 Conference, the Future We Want, underscores climate change as "an inevitable and urgent global challenge with long-term Implications for the sustainable development of all countries". Through the document, Member States express their concern about the continuous rising of emissions of greenhouse gases and the vulnerability of all countries, particularly developing countries, to the adverse impacts of climate change.

Correct option is B

Inevitable means certain to happen; unavoidable.
Synonyms: Unavoidable, inescapable, certain.
Antonyms: Avoidable, uncertain, preventable.
Meanings of all four options:
Immemorable: Not memorable; not easily remembered or noteworthy.
Undeniable: Unable to be denied or disputed; unquestionably true or certain.
Adventurous: Willing to take risks or try out new methods, ideas, or experiences.
Escapable: Able to be avoided or evaded.