If an individual has the genotype Dd, what alleles can it pass on to its offspring?

Both "D" and "d" allele

Explanation:

As per the principle of segregation proposed by mendel, an allele pair can split in to two during cell division in a way such that it can give both of its allele (with in an allele pair) to its offspring.

Thus by that logic anyone with a genotype Dd, can segregate its allele pair to pass both "D" and "d" allele to its offspring.

Sam (father) DD homozygous dominant

Sally (mother) dd homozygous recessive

Susan (child) Dd heterozygous

:3