A

Step 1: Understand dispersive power.
Dispersive power refers to the ability of a material to separate light into its constituent colors. This property is essential in optics, particularly in lenses and prisms.

Step 2: Compare materials.
Flint glass is known for its high refractive index and also exhibits a higher dispersion compared to crown glass. It is more effective at splitting light into its spectrum due to its composition, which includes lead oxide.

Step 3: Analyze the options.
- Option A: Flint glass - Known for maximum dispersive power.
- Option B: Crown glass - Exhibits lower dispersive power than flint glass.
- Option C: Mixture of both - Would likely result in average properties, not maximum dispersive power.
- Option D: None of the above - Incorrect since Flint glass is a valid option.

Conclusion: Since Flint glass has the maximum dispersive power of the materials listed, the correct answer is A.