Which of the Following Statements Best Describes the Function of the α

Which of the following statements best describes the function of the α factor secreted by yeast cells?

A) It binds to receptors on α cells to stimulate mating between α cells.
B) It binds to receptors on α cells to stimulate mating between a cells and α cells.
C) It binds to receptors on a cells to stimulate mating between a cells.
D) It diffuses through the membranes of a cells, binds to DNA and initiates transcription of a factor genes.