My answer to that challenge is to read a book called "Darwin's Black Box". I think the author's name is Michael Behe. If you're serious about getting an answer to your question you will read this book.
The vast majority of Darwin's Black Box is dedicated to shooting down the theory of evolution rather than providing positive, objective evidence of intelligent design a/k/a creationism. The author takes the view that intelligent design must be the force behind life as we know it because Darwinism is less than perfect. I could justy as easily say that every spieces of life was placed on earth by extra terrestrials and since you can't disprove my theory, it must be true. That is not science, my friend.