b
(B) \(\frac{{{\lambda _{\text{x}}}}}{{{\lambda _{\text{y}}}}} = \frac{{{m_y} \times {v_y}}}{{{m_x} \times {v_x}}}\,\,\,\, \Rightarrow \,\,\,\,\frac{1}{{{\lambda _y}}} = \frac{{\frac{{25}}{{100}}{m_x}.\frac{{75}}{{100}}{v_x}}}{{{m_x}{v_x}}}\,\, \Rightarrow \,{\lambda _y} = \frac{{16}}{3} = 5.33\,\mathop A\limits^o\)