Answer:
Nitrogen is the right answer.
The Moon is thought to have come from the Earth. In 1975, the giant impact hypothesis was put forward. This suggests that the Earth was hit by a planet about the size of Mars around the time of the formation of the solar system approximately 4.5 billion years ago, and the impact caused part of the outer layer of the Earth to spin off and form what is now the Moon.
The correct answer to this question would be "B", co-dominance.
Helper T cells become activated by interacting with antigen presenting cells. and the second blank space is either cytotoxic t cells or B cells
