Which of the following statements is true?

Accretions are a type of growth or increase, while accessions are the process of receiving and adding items to a collection. Therefore, all accretions are accessions, but not all accessions are necessarily accretions. Option A is incorrect because not all accessions are accretions. Option C is incorrect because accretions and accessions are related as explained above. Option D is incorrect because there is no general rule about the frequency of accretions versus accessions.