Answer: Option B
$$\eqalign{
& {a^2} + {b^2} + {c^2} = 16,{\text{ }}{x^2} + {y^2} + {z^2} = 25{\text{ }} \cr
& {\text{But }}b = c = 0,{\text{ But }}y = z = 0 \cr
& {\text{}}a = 4{\text{ }}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 5 \cr
& {\text{Now, }} \cr
& ax + by + cz = 20 \cr
& 4 \times 5 + 0 + 0 = 20 \cr
& 20 = 20{\text{ }}\left( {{\text{Satisfy}}} \right) \cr
& {\text{Now, }}\frac{{a + b + c}}{{x + y + z}} \cr
& = \frac{{4 + 0 + 0}}{{5 + 0 + 0}} \cr
& = \frac{4}{5} \cr} $$