Select the most appropriate option to substitute the underlined segment in the given sentence. If there is no need to substitute it, select 'No replacement required'.

After lengthy deliberations, the board of directors finally came round the proposed merger.

The correct answer is came around to the proposed merger.

Explanation:
The underlined segment "came round the" is grammatically incorrect in this context.

The phrasal verb "come around to" (or "come round to") means to change one's opinion or gradually accept/agree with an idea, plan, or proposal after initial hesitation or deliberation. In the sentence, the context of "After lengthy deliberations" shows that the board of directors eventually agreed to the proposed merger. Therefore, the preposition "to" is required, making "came around to the proposed merger" the correct substitution.

Meaning of other options:
- came towards: Refers to moving physically closer to something or someone.
- came about: Means to happen, occur, or take place.
- came across: Means to meet or find something unexpectedly or by chance.
- No replacement required: Incorrect because "came round the" is missing the required preposition "to".