If 1 is A, then Emily Eden and Fanny Parks formed the basis. But actually journals formed the basis.
IMHO: 2 is C (a large staff members in D is ridiculous, for "members" is plural and so takes no article). C is the most parallel too.
As for Q#1, I still have different opinion.
~~~~~keeping journals which form the basis of
journals forming the basis of
Wheteher I have missing point about grammar?
As for Q#2, the correct answer is D
I have a mistake on typing that not is "a large staff members, but is "a large staff".
I also prefer to C answer.