Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following.

In dry weather, the bulliform cells of grasses present in the upper epidermis become flaccid, which triggers the inward rolling of lamina to hide stomata to minimize transpiration.
(1) Tyloses of vessels obstruct the flow of water in heart wood and such wood becomes functionless.
(2) Stomatal closure is due to flaccidity of guard cells.
(4) There is no shrinkage of air spaces in spongy tissue of grass leaf.