The troposphere is the lowest level of the atmosphere, so it is in contact with the Earth's surface. In contrast, the stratosphere is located above the troposphere, so it is not in contact with the Earth's surface. ... The air density and air pressure are much lower in the stratosphere.
Answer:
1. more than 14 days of headaches over three months in a row.
Answer: D. The lover's initials were carved on the tree.
Explanation:
The modifier in the sentence makes it seem as though lovers were the ones carved on the tree instead of the initials being the ones carved on the tree.
This should be corrected to reflect that the initials were the ones carved on the tree and that they belong to the lovers. Option D gives the best option because in using the possessive ('s), it made it appear that the lovers owned the initials that were carved on the tree.