Answer:
It is the trickiest door to open.
Step-by-step explanation:
The phrase that explicitly states the author's attitude about the voice is the first one. If we find the same phrase in the text (I find this one the trickiest to open), we can see that it's preceded by words I find. This means that he personally considers that door the trickiest to open. That is his attitude, and he reveals it to us explicitly, leaving no room for doubt.
The rest of the statements are incorrect because:
- Ancients using the voice is a fact. That is not an opinion.
- Statements that only the writer hears the voice and that the reader will always hear it are incorrect. The sentence from the passage that proves this is: If the writer can truly hear the voice of a character, so will the reader.