A femur is a leg bone found in a human skeleton. When evaluating the human body's levels of organization, a femur is best classified as — A.
an organ, because it is part of the skeletal system.
B.
an organ system, because it is composed of many cells.
C.
an organelle, because it is composed of many tissues.
D.
an organism, because it is part of the skeletal system.

Option A

Explanation:

The femur is classified as an organ, because it is part of the skeletal system

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed

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