Sorry this is late but...
Answer:
B:Places a great deal of pressure on himself
Step-by-step explanation:
Because "You tell me that I shall astonish the world if I make out the demotic inscription on the Rosetta Stone. On the contrary, I think it astonishing that It should not have been made out already, and that I should find the task so difficult.” really puts some self pressure on him to find out what the Rosetta Stone says
Hope this helps and sorry that no one answered for the time you needed it