Correct option is D
The word that can be filled in the blank is
‘poses’ to make the sentence grammatically and contextually correct.
•
‘Poses’ is the simple present tense form of the verb, used to indicate a current or general truth, which is appropriate here since climate change is
currently a threat.
• As per the context, the word ‘poses’ fits in very well & hence, it is the correct option.
Meanings of other given words and why they are incorrect:
•
will be posing – (future continuous tense; suggests ongoing future action – incorrect as the threat is already present.)
•
posed – (past tense; implies the threat was in the past – incorrect.)
•
will pose – (simple future tense; implies the threat is only in the future – incorrect as the threat exists now.)
• Thus, all the other given words imply different time references and do not fit in the context of the present urgency.