The main function of the cell wall is to
a. support and protect the cell.
c. direct the activities of the cell.
b. store dna.
d. the cell move.

The main function of the cell wall is to support and protect the cell.  

Cell membranes or walls envelope the whole cell. Cellulose-made membranes are found on plant cell and some organisms. In other species such as protozoa or bacteria, cell walls are made of chitin. Cell walls protect the cell by being semi-permeable, in the sense that, it chooses what substances the cell must accommodate to sustain its functions. Support as it became the cell’s backbone and skeleton for its shape. In plants, cell walls also help the cell as it grows taller. 

Resistance than a bicycle? i'm not entirely sure

Carbon-14 has a half-life of 5,730 years and most igneous rock is older than that.