This is a slightly tricky question in which we have to pick the options after carefully comparing them with the others. The first sentence says that artificial embryo twinning is low-tech. The second sentence says that it mimics the natural process that creates identical twins. Option 4 very much captures the key ideas. In option 1 , the word 'unlike' shows dissimilarity, but the passage focuses on similarity, not dissimilarity. Option 1 goes out. Option 3 says twins are formed during fertilization, but the passage says that the twins are formed after fertilization. Option 2 is close to 4 but does not clearly specify the exact time when the embryo splits into two. Moreover, the passage says mimics, while option 4 says 'close to', which is a slight distortion of the facts as given in the passage.