The correct answer is: C. Either I or II is implicit.
The statement “Today I must satisfy myself only by looking at a pink headed duck in an encyclopedia” does not provide enough information to determine whether or not assumption I is implicit. It is possible that pink headed ducks are as good as extinct now, but it is also possible that they are still in existence but the speaker is unable to see them for some other reason. Similarly, the statement does not provide enough information to determine whether or not assumption II is implicit. It is possible that people refer to encyclopedia to know only about things which do not exist now, but it is also possible that they refer to encyclopedia to learn about things that do exist but are not familiar to them. Therefore, either assumption I or assumption II could be implicit in the statement, but both assumptions cannot be implicit.
Here is a more detailed explanation of each option:
- Option A: Only assumption I is implicit. This option is incorrect because assumption I is not necessarily implicit in the statement. As explained above, it is possible that pink headed ducks are still in existence but the speaker is unable to see them for some other reason.
- Option B: Only assumption II is implicit. This option is incorrect because assumption II is not necessarily implicit in the statement. As explained above, it is possible that people refer to encyclopedia to learn about things that do exist but are not familiar to them.
- Option C: Either I or II is implicit. This option is correct because either assumption I or assumption II could be implicit in the statement, but both assumptions cannot be implicit.
- Option D: Neither I nor II is implicit. This option is incorrect because assumption I or assumption II could be implicit in the statement.
- Option E: Both I and II are implicit. This option is incorrect because both assumptions cannot be implicit.