Answer is : (b) Tobacco leaf has more stomata on the lower surface
Tobacco is a dicot plant, thus its leaves have more number of stomata on its lower surface. If you cover the leaves of a healthy plant with vaseline, it will block its stomata and therefore it will not lose water through transpiration, so the upward movement of the water in the plant will stop. This will not allow the plant to wilt quickly.
The leaf ‘2’ is smeared with vaseline on the upper surface, so the plant will lose water from the lower surface and in leaf ‘3’, vaseline is smeared on the lower surface therefore the water is lost from the upper surface. But the number of stomata are more on the lower surface therefore leaf ‘2’ will wilt more quickly than leaf ‘3’.