What causes flaming combustion to occur?

select one:
a. a solid fuel mixes with an adequate amount of liquid fuel to be able to sustain an open burning flame.
b. a gaseous fuel mixes with an adequate amount of oxygen and heats to ignition temperature.
c. a solid fuel encounters an open flame and entrains enough air to ignite.
d. a gaseous fuel encounters an external heat source and experiences piloted ignition.

Answer is A(Soild Fuil

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speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..