The correct answer would be through adaptation and eventually over time they had to evolve to the area around them which made them develop over time to have longer necks .
Continental plate moving on the sea floor.
A sacromere is a segment between two adjacent Z discs and are essential for the striated structure of the cardiac and skeletal muscles.
<u>Explanation:</u>
The Z disc is surrounded by the I band made of thin filament called actin. The I band is followed by the A band made up of thick filament called myosin. When the muscles contract the actin and the myosin become superimposed/overlapped.
The sliding filament model explains the contraction of the sacromere in which the Z discs move closer due to the overlapping of the thin and thick filaments. Thus the I band moves close to the A band which remain the same length as shown in figure.
DNA has 3 components; phosphate, a sugar called deoxyribose (a 5 carbon sugar as opposed to the sugar in the picture which is a 6 carbon sugar - glucose) and a nitrogenous base (adenine, thymine, guanosine or cytosine). So if you look at those 3 pictures, the only one is the nucleotide that's part of the DNA.
Re-read the question: the presence of phosphorous is the answer!!