The correct option is A taking my life in my hands
The appropriate second half of the sentence is Option D), making it the correct answer. This is because out of all the options presented, it goes the best with the first half in terms of context as well grammar; that is the speaker acknowledges that he /she walked to the very edge of the diving board, risking his life. Further, to 'take one's life into one's hand' is a common idiom as well. The other options are either irrelevant or don't make sense.