'画期的 (kakkiteki)' means groundbreaking or epoch-making, referring to something that marks a new era or brings about significant change in a field. The discovery of iPS cells is a perfect example. Choice 2 is an exaggeration for taste; '格別な' (exceptional) or '素晴らしい' (wonderful) is better. Choice 3 misuses it for fashion; '個性的' (unique) or '奇抜' (eccentric) would fit. Choice 4 is an overstatement for a simple shortcut; '素晴らしい' (great) or 'うまい' (clever) would be more natural.