Final answer:
The fourth adaptation of marram grass is rolled leaves, which help conserve moisture by reducing exposed leaf surface.
Step-by-step explanation:
The fourth modification demonstrated by marram grass is c. Rolled leaves. Marram grass is a coastal plant that has evolved several adaptations to survive in its harsh, sandy environment. One of these adaptations is having rolled leaves, which help to reduce water loss by minimizing the surface area exposed to the sun and wind. Unlike a. Increased chlorophyll content, b. Thick cuticle, and d. Deep root system, which are other potential adaptations to environmental conditions, the specific adaptation of marram grass related to leaf structure is its tendency for the leaves to roll inwards, conserving moisture.