In the following question, few sentences are given with two blanks in each. Select the pair of words that best completes both blanks in all the sentences, ensuring the sentences remain grammatically correct and contextually appropriate.

(I) He ____________ that the sudden ____________ in temperature signals an approaching storm.
(II) The committee ____________ the ____________ of the project’s budget is justified by the expanded scope.
(III) She ____________ that his recent ____________ to department head will bring positive changes.

The correct option is presumes; elevation.

Let us analyze how this pair of words fits grammatically and contextually into all three sentences:

Sentence (I):
"He presumes that the sudden elevation in temperature signals an approaching storm."
Here, presumes (a verb meaning to suppose or assume something on the basis of probability) fits the action of forming a belief about an approaching storm based on temperature, while elevation (a noun meaning a rise or increase) logically describes a change in temperature.

Sentence (II):
"The committee presumes that the elevation of the project’s budget is justified by the expanded scope."
Here, presumes fits as the committee's stance/assumption, and elevation appropriately refers to an increase or step-up in budget.

Sentence (III):
"She presumes that his recent elevation to department head will bring positive changes."
Here, presumes functions correctly as her expectation or assumption, and elevation accurately means promotion or advancement to a higher position/rank.

Since the pair "presumes; elevation" maintains proper subject-verb agreement, correct tense, and precise contextual meaning across all three sentences, it is the correct answer.