In a BJT, α and β are related by the expression:

• A. \(\alpha = \frac{1}{{1 - \beta }}\)
• B. \(\alpha = \frac{1}{{1 + \beta }}\)
• C. \(\alpha = \frac{\beta }{{1 - \beta }}\)
• D. \(\alpha = \frac{\beta }{{1 + \beta }}\)