An investor wants to reduce the unsystematic risk in her portfolio. Which of the following actions is least likely to do so$?$

A$)$ Reducing the number of stocks held in her stock portfolio

B$)$ Adding bonds to her stock portfolio

C$)$ Adding international securities into her portfolio of U$.$S$.$ stocks

D$)$ Adding U$.$S$.$ Treasury bills to her risky portfolio

E$)$ Adding technology stocks to her portfolio of industrial stocks