Since this is an ASSUMPTION question and the best way to solve this is to negate the choice and that should break the author's conclusion .
Conclusion : Shakespeare must have been finished writing sonnets after 1595 but before 1600. It cannot have been written earlier than 1595 and after 1600.
Premises :
1.one of the sonnets references a monument in London that was not erected until 1595.
2.it is written with a type of ink that Shakespeare is known to have stopped using after 1600
Our MAIN goal is to find something that will negate the conclusion, i.e,
that will make us believe that Shakespeare might have written sonnets before 1595 OR after 1600. Note that OR is used because we just want to crack the conclusion which can be done in either way .
Option choices:
(A) No stocks of the abandoned ink existed after 1600
Incorrect : After negating we get that - Stocks of abandoned ink
existed after 1600. Does it break the conclusion. A big NO. Even if the stock existed it is known that Shakespeare stopped using it after 1600.
(B) The parchment on which the sonnets are written cannot be tested accurately to determine its age.
Incorrect : Irrelevant. Shakespeare has written in those parchments only gives us one info that they were already available. Whether the parchments were made in 1400 or 1500 will not contribute in any way as the passage is concerned with the sonnets written in it.
(C) The monument referenced in the sonnet was familiar to general public in 1595
Incorrect : Irrelevant . We are concerned with Shakespeare and not general public.
(D) Shakespeare did not write the sonnets of the collection overall several years
Correct . Negation - Shakespeare did write the sonnets of the collection overall several years.
Now think what if this is true. This can be true in two ways :
1. What if Shakespeare started writing the sonnets before 1595. The passage tells us that
one of the sonnets references a monument in London that was not erected until 1595. So what . Is it necessary to write about a building only after it was erected ? What if he referred to the building when it was under construction? Yes, it can be done . So this choice will negate the conclusion.
2.What if the Shakespeare completed the sonnets after 1600. The passage tells that
Shakespeare is known to have stopped using a a type of ink when a better alternative was introduced on the market that year. So what. What if he wrote half the sonnets using a type of ink and other half using another type of ink. Yes, it can be done . So this choice will again negate the conclusion.
So this is our required choice.
(Note : Here we can also go ahead and consider a case where Shakespeare started writing sonnets in 1596 and completed in 1599, which does fall into the range. This doesn't negate the conclusion then.
But we need to make sure what our main goal is .
We have to negate the choices and find something which will break the conclusion. And we did find not one but two such cases.
Many a times, we are too strict and leave a choice because it contains 2 scenarios and only 1 of them negates the conclusion. Simply avoid that.
We need to be clear that
an ASSUMPTION is something that MUST ALWAYS BE TRUE. If we are able to find even a single case in which it breaks, that's our choice.)
(E) Shakespeare's style of poetry did not change between 1595 and 1600
Incorrect: Irrelevant . No relation has been given in the passage between Shakespeare's style of poetry and his timing of writing sonnets.