Please help me with the question below:

You have read an article in the Wall Street Journal that has convinced you to consider investing all your wealth in X Corp stock. If you decide to go through with this investment, you will hold no assets other than X Corp. stock. When evaluating X Corp. stocks risk, you should consider

A. its systematic risk measured using Beta

B. first its systematic risk (Beta) and then its total risk (sigma)

C. its unsystematic risk, measured using (1-rho)xSigma, where rho is the correlation with the rate of return on the market portfolio.

D. its total risk measured using Sigma (s. d. of return)