Create a vibrant and eye-catching thumbnail for a quiz video. The design should feature a bold, colorful gradient background in blue, purple, and pink. Place a large, central question mark with a 3D effect or glowing outline to make it stand out. Surround the question mark with icons or illustrations of math symbols, history books, science beakers, and word puzzles. Add the text "Quiz Time!" at the top in a fun, playful font, in a bright color like yellow or white for contrast. Include a secondary text line at the bottom that says "Test Your Knowledge!" in a slightly smaller, complementary font. Incorporate small icons of a clock, light bulb, and trophy to suggest challenge, thinking, and winning. Use a border or shadow effect to frame the thumbnail and enhance its visual appeal. The overall design should be dynamic and energetic, capturing the excitement and fun of taking quizzes.