Sentence Correction

As per Ron's reasoning provided at the https://www.manhattangmat.com/forums/pos ... 4622,nouns that are modified by prepositional phrases can still be the referent of 'which' even if they are a few words distant from it.
For example: "The picture of my brothers, which was taken last year in Mexico, is one of my favorites."

Here, which can refer to the picture.

However, if I look at the below question, D-40 of OG 12, a doubt appears in my mind..

In 1995 Richard Stallman, a well-known critic of the
patent system, testified in Patent Office hearings
that, to test the system, a colleague of his had
managed to win a patent for one of Kirchhoff's laws,
an observation about electric current first made in
1845 and now included in virtually every textbook of
elementary physics

A) laws, an observation about electric current first
made in 1845 and
(B) laws, which was an observation about electric
current first made in 1845 and it is
(C) laws, namely, it was an observation about
electric current first made in 1845 and
(D) laws, an observation about electric current first
made in 1845, it is
(E) laws that was an observation about electric
current, first made in 1845, and is


Here, OG says that in option B-
Which is ambiguous because it could refer to
one or to laws; it is violates the parallelism of
first made and now included.

But according to Ron's comment, which can refer to one unambiguously. Please let me know what I am missing.

Thanks !