A is mostly likely your answer.
Gregor Mendel was the "father of modern genetics" and helped disprove the blended theory of inheritance.
DNA replication occurs in the nucleus. (The nucleus has a specific environment that ensures DNA is not degraded)
Transcription of genes to result in RNA occurs in the nucleus. RNA processing (e.g. the addition of a poly-A tail to each 3' end of mRNA) occurs in the nucleus as well.
Translation occurs in the cytoplasm.
Hope this helps! :)