Recently discovered fossil remains strongly suggest that the Australian egg-laying mammals of today are a branch of the main stem of mammalian evolution a common ancestor of mammals more than 220 million years ago.
a. rather than developing independently from
b. rather than a type that developed independently from
c. rather than a type whose development was independent of
d. instead of developing independently from
e. instead of a development that was independent of

B). Rather than a type that developed independently from.

Explanation:

As per the question, option B i.e. 'rather than a type that developed independently from' displays the most appropriate option to fill the given blank as it contains a parallel structure('a type' is parallel to 'a branch') that assists in conveying the intended meaning clearly and effectively. The other options either contain a parallelism error(option A and D due to incorrect use of noun phrase) or logically unparalleled (option E). Therefore, option B displays the sentence that is both grammatically appropriate and lexically coherent.  

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