Born in 1860 in Kirriemuir, a burgh in Scotland, and viewing life as a

I am no expert, but I will try to explain why D is wrong and why viewing is better than viewed.

Substitute option D, and we get
He was born in 1860 in Kirriemuir, a burgh in Scotland, and he viewed life as a great adventure, James M. Barrie, the author of Peter Pan, in his classic story of Never Never Land emphasized on the theme of childlike innocence.
Three Independent Clauses:
1. He was born in 1860 in Kirriemuir, a burgh in Scotland
2. he viewed life as a great adventure
3. James M. Barrie, the author of Peter Pan, in his classic story of Never Never Land emphasized on the theme of childlike innocence.

Clauses 1 and 2 are connected by a conjunction 'and'. Clauses 2 and 3 are connected by a comma. Technically, this is comma splice error. i.e, Two Independent clauses must be connected by a conjunction else the connection is called comma splice, which is not acceptable in GMAT>

Now to answer your second question, why viewing is better than viewed.
2 basic types of modifiers:
,+Verb+ing modifiers - modify the preceding clause or the entire preceding clause (if placed after a clause)
Verb+ing modifiers - modify the nearest noun
Verb+ed modifiers - When placed in beginning of the sentence, modifies the noun.

Now, grammatically 'Born' and 'viewed' modify JMB. But here is the catch. When did he view? If we use born, it's one time activity. He was born and the action is completed. But did we get any such context as to from when to when did JMB viewed Life as X? We don't know. So, instead of V+ed modifier, V+ing modifier is preferred.

Does this answer your question?