The company's strategy involves not only streamlining operational processes and reducing overhead but also to expand into emerging markets and developing new product lines.
Correct: B
The 'not only X but also Y' construction requires X and Y to be grammatically parallel. In the original sentence, X is 'streamlining operational processes and reducing overhead' (two gerund phrases). Y, however, is 'to expand into emerging markets and developing new product lines' (an infinitive phrase followed by a gerund phrase). This breaks parallelism. Option B correctly uses parallel gerund phrases for both parts of the construction: 'not only streamlining operational processes and reducing overhead but also expanding into emerging markets and developing new product lines.' Option C uses infinitives for both, which would also be parallel, but 'involves streamlining' is already established, making the gerund form more consistent and concise. Option D uses noun phrases ('the expansion,' 'the development'), which breaks parallelism with the initial gerunds. Option E incorrectly alters the 'not only... but also' structure.