Which sentence does not contain any punctuation errors?
a. thinking about it now, i realize that i was wrong.
b. thinking about it now i realize, that i was wrong.
c. thinking about it now i realize that i was wrong.
d. thinking, about it now, i realize that i was wrong.

The sentence that does not contain any punctuation errors is A) Thinking about it now, I realize that I was wrong.
There has to be a comma after now, because the whole order in the sentence is inverted.

The answer to the English question presented above would be letter a. Thinking about it now, I realize that I was wrong. The sentence that does not contain any punctuation errors would be 'Thinking about it now, I realize that I was wrong.'. All the other choices are not applicable.

That's something your gonna have to yourself with buddy!