Statement: Today I must satisfy myself only by looking at a pink headed duck in an encyclopaedia.
Assumptions:
1. Pink headed ducks are as good as extinct now.
2. People refer to encyclopaedia to know only about things which do not exist now.
Answer: A
Since the narrator talks of satisfying himself by just looking at a picture in encyclopaedia, it means that pink headed ducks are not to be seen alive. So, I is implicit. But II does not follow from the statement and is not implicit.