The Grand Canyon is an example of physical weathering.
Another example is a landscape called karst formed by chemical weathering
Tone is the attitude of the story teller when telling the story
The answer is B, promised.
"He promised to pay his bills"
Kate could not attend the senior class trip although she earned straight A's. This is one way you can combine the two sentences with a subordinate conjunction - in this case it is the word 'although.'