Probably for the umbilical cord that connects babies (from their early stages in the womb to their removal) to their mothers. The cord is cut, forming the belly button. This is analogous to astronauts in space.
Answer: C
Explanation: weak nuclear
According to the inverse square law of light, <span>apparent brightness will decrease by a factor of 9. Use the formula </span>

, to check it.
That's true.
They're radio waves, at the frequency of 2.45 GHz (in all microwave appliances manufactured in the US).