HSK6 (H61329) Q.69 about "由厚到薄" vs. "由薄到厚": How can we conclude the correct answer is 3.?

Question

This is HSK6 past exam H61329 question 69 (fill-in-the-blank).

华罗庚把读书过程总结为“由厚到薄”和“由薄到厚”两个阶段。当你对书的内容有了_____的了解，抓住了全书的_____时，书就由厚变薄了。如果在读书过程中，你还能对各章节做深入_____，在每页上添加注解，_____参考资料，书又会愈读愈厚。读书就是由厚到薄，再由薄到厚的双向过程。

1. 细致 课题 检讨 补救
2. 精致 主题 探测 弥补
3. 透彻 要点 探讨 补充
4. 彻底 重心 探索 补偿

We can eliminate 1. and 2. easily based on the first blank. But I'm struggling to figure out how to come to the correct answer (3.). I answered 4. because I thought 探讨 required verbal discussion, and 补充参考资料 seemed to imply 你 is adding to the reference literature, not the other way around.

Question: How can we conclude the correct answer is 3.?

Answer 1

Question: How can we conclude the correct answer is 3.?

by the process of elimination

1. 补救 (mend/ repair) doesn't fit 参考资料 (reference), you can't mend the reference material

2. 弥补 (compensate) doesn't fit 参考资料 (reference), you cannot compensate the reference material

3. 补偿 (compensate) doesn't fit 参考资料 (reference), you cannot compensate the reference material

I thought 探讨 required verbal discussion

探讨(investigate) is not 讨论 (discuss), it can be done on your own. 讨 has the meaning of 'request/seek' e.g. 讨債，讨公道

补充参考资料 seemed to imply 你 is adding to the reference literature, not the other way around.

补充 (replenishing) here means 'add' more reference to your study, not 'add thing' to the reference

Answer 2

By inspection, answer (4) is eliminated, because the phrase "补偿参考资料" - "compensate the reference material" does not make sense. The correct fill-in shall be "补充" - "replenish" the reference material.