c.midrib. The petiole is a stalk arising from the stem of the plant that connects the stem to the leaf blade. In the middle of the leaf blade is the midrib, which is an extension of the petiole.
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Explanation:
Organisms have different forms of circulatory systems. Humans have a closed circulatory system, while many mollusks and other invertebrates have an open system. In a closed circulatory system, blood is enclosed within blood vessels.
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.
