Which part of a bone such as the femur enables the bone to get longer? a. the growth plate b. the bone marrow c. the compact bone tissue d. the spongy bone tissue

Answer;
The growth plate.
 It is the part of a bone such as the femur enables the bone to get longer

Explanation;
The growth plate is also known as the epiphyseal plate or physis.
It is the area of growing tissue near the end of the long bones such as the bones of the arm and legs, in children and adolescents. 
It determines the future length and shape of the mature bone.
Each long bones has at least two growth plates, one at each end. 

It's cell theory. easy name i would think.