The process which planetesimals combine with other planetesimals is called Accretion.
There are other names which refer to as accretion. For example, Accretion geology is termed as the increase in the size of a tectonic plate by addition of materials which convergent boundary.
Accretion atmosphere is termed as the process by which water vapor which is in clouds forms water droplets around nucleation sites.
Accretion astrophysics is termed as the formation of planets and other bodies through a collection of material through gravity.
C is the answer
:) for your question (im writing extra cause answer is too small)
The two chromatids of a duplicated chromosome are held together at a region of DNA called the centromere. Centromeres are the attachment points for microtubules, which are responsible for the guiding the movement of chromosomes during mitosis and meiosis.
