Plants hold the capacity to grow throughout their life because of

The correct option is B meristems
Meristematic cells are the cells that are capable of dividing. Apical and lateral meristems aid in the plant growth. Apical meristems are found at the apical portions of plants like the shoot apex and root apex, and are continuously dividing cells. They add to the primary or the vertical growth of plants. Lateral meristems help in the horizontal growth or increase in the girth of the plants.

These meristematic cells have thin cellulosic walls, dense protoplasm and large conspicuous nucleus. Plasmodesmatal connections occur abundantly in them. They have the ability to grow and divide. These are small immature cells, isodiametric, rounded, oval or polygonal. There are no intercellular spaces. Vacuoles are absent or very small. Endoplasmic reticulum is small. Mitochondria have very simple structures and the rate of respiration is very high.

In gymnosperms and dicots, lateral meristems cause the secondary growth that is responsible for increasing the girth of the plants.

Leaves are the vegetative appendages of a plant and are responsible for carrying out photosynthesis. They provide food which is required for growth but don’t contribute directly to any growth parameter.

Sunlight acts as a source of energy for photosynthesis to be carried out and also orients the shoot growth direction. But plants exhibit growth during the night as well, when there is no sunlight.

Senescence is the arrest in growth and halting of cell division. As a result, deterioration of parts or whole plant can occur. Senescence is observed in all plants.