1 is false, waves can't propagate in a vacuum.
Answer: No se como hacer el cálculo
Explanation: Aún así creo que la opcion es la C
Answer:
Crayon.
Explanation:
A crayon is known to be a kind of stick like pencil, but made of called wax, and it is useful for painting.
It is known that that the first crayon which looks like the modern crayon was made in Europe. And it was initially or originally made then out of the mixture of charcoal and oil. But now, the charcoal has since been replaced by various pigment and the oil been replaced by wax. This because the wax provides a better and stronger writing stick and it is easier to work with.
It should be noted, that crayon is used for writing and drawing, and its invention can be dated back to 18th century.
