You can tell the age of a skeleton by looking at: O1) the length of the femur
O2) the shape of the pelvis
O 3) the number of fused bones
O4) the color of the bones

Calculating the age of a skeleton can be done by looking at the number of fused bones (option 3).

Explanation:

The calculation of skeleton bone age takes into account the complete ossification of bones, which occurs at various stages of human development.

In childhood, the epiphyses or ends of long bones are not completely ossified but are formed by cartilage, due to the process of growth. When development is achieved, the growth nuclei and cartilage disappear.

Bone age is a reliable parameter for calculating chronological age, as they are quite approximate.

The other options are not correct because:

   1. The length of the femur is useful for calculating height.

   2. The shape of the pelvis helps to differentiate the sex.

   4. The color of the bones is not a useful parameter to calculate the age of the skeleton.