Aneuploidy is a chromosomal disorder characterized by an abnormal number of chromosomes, which is not an exact multiple of the haploid set. The primary causes of aneuploidy are related to the addition (gain) or deletion (loss) of chromosomes or chromosomal segments.

Let's examine the options given:

A. Substitution - This involves replacing one segment of a chromosome with another, which generally does not alter the chromosome number.

B. Addition - This involves the gain of an extra chromosome or chromosomal segment, which directly causes aneuploidy.

C. Deletion - This involves the loss of a chromosome or chromosomal segment, which also directly causes aneuploidy.

D. Translocation - This involves the rearrangement of parts between nonhomologous chromosomes and typically does not change the overall chromosome number.

E. Inversion - This involves a part of the chromosome being reversed end to end, which does not usually cause a change in the chromosome number.

Based on the explanation above, the most appropriate causes of aneuploidy from the options provided would be B (Addition) and C (Deletion).

Therefore, the correct choice is:

Option D

B and C only