The world needs a/an ______ that addresses climate change smartly without scaring us needlessly and that pays heed to the many other challenges _________ the planet.

The sentence highlights the need for a plan that addresses climate change and all other challenges faced by our planet. For the first blank, we need a noun here as denoted by the use of the article A/AN (articles are used to modify only nouns). APPROACH fits contextually. Your approach to a task, problem, or situation is the way you deal with it or think about it. SERVICE(the action of helping or doing work for someone) and YIELD (an amount produced of an agricultural or industrial product) does not fit contextually. For the second blank, we need a verb to link the subject (CHALLENGES) and the object(THE PLANET). FACING((of a problem or difficult situation) present itself to and require action from (someone)) and CONFRONTING(If you are confronted with a problem, task, or difficulty, you have to deal with it) fit contextually. LOOKING(direct one's gaze in a specified direction) does not fit contextually. Thus, (d) is the right answer.