Final answer:
In interval notation, I represents increasing, D represents decreasing, and C represents constant.
Step-by-step explanation:
a. In interval notation, I represents increasing, D represents decreasing, and C represents constant.
b. In interval notation, + represents increasing, - represents decreasing, and 0 represents constant.
c. In interval notation, ↑ represents increasing, ↓ represents decreasing, and ↔ represents constant.
d. In interval notation, Inc represents increasing, Dec represents decreasing, and Const represents constant.