Which process is most critical for different types of tree cells to develop a) mitosis b) cell differentiation c) sexual reproduction d) dna replication

The correct option is "B", that is cell differentiation.
Cell differentiation is the process that is most critical for different types of tree cells to develop and in this process the cells which are less specialized become more specialized or we can say that cell types are changed into another type of cells. when the multi-cellular organisms are developed, during the development period differentiation occurs many times.