Either C or D. Those r the answers that make more sense.
Answer: Because hydrogen is a gas.
Explanation: If children were running around with balloons filled with hydrogen gas, then they would catch fire. So the answer to your question is, its simply dangerous.
A is the answer im pretty sure
"As we move through the visible spectrum of violet, blue, green, yellow, orange and red, the wavelengths become longer. The range of wavelengths (400 - 700 nm) of visible light is centrally located in the electromagnetic spectrum (Fig. 1)."
-https://www.asu.edu/courses/phs208/patternsbb/PiN/rdg/color/color.shtml
