Part of the given sentence is underlined. Choose the answer choice which is…

Concept: When a sentence compares two parallel quantities or rates using a connector like ‘while’, ‘whereas’, or ‘but’, both sides of the comparison must share the same grammatical structure (a matching noun phrase) and correct subject-verb agreement. Substituting a pronoun such as ‘those’ for one side breaks this parallelism unless a clear plural antecedent already exists.

Application: Here the sentence sets up a comparison: ‘the rate of addition to wooded lands will drop while ___.’ The blank must repeat the noun phrase ‘the rate of’ to stay parallel, and its verb must agree with the singular noun ‘rate’. Checking each option against this requirement:

• ‘those of loss rise’ uses the plural pronoun ‘those’, but the only earlier noun it could refer to is the singular ‘rate’ — a structural mismatch.

• ‘it rises for loss’ abandons the noun-phrase pattern entirely and is unidiomatic phrasing.

• ‘those of losses rise’ keeps the same mismatched pronoun and additionally shifts ‘loss’ to the plural ‘losses’, changing the intended meaning.

• ‘the rate of loss rises’ repeats the noun phrase ‘the rate of’ and pairs the singular subject ‘rate’ with the singular verb ‘rises’ — fully parallel with the first half of the sentence.

Cross-check: Reading the corrected sentence back confirms the fix: ‘The World Forestry Association has predicted that the rate of addition to wooded lands will drop while the rate of loss rises.’ Both clauses now share the identical ‘the rate of ___’ structure with singular verb agreement — the hallmark of correctly parallel comparison.