Answer:
1) C
2) Semicolon(Before "many")
3) Colon(Before Helen)
4) Colon (Before"imagination")
5) Colons(Before 30 in 830 and before 15 in 915)
Step-by-step explanation:
A colon is used when items are about to be listed. For example, On the table are different items which include: a cup, a book and a pencil. A colon is used for timing, for example, 7:30am. Colon is an essential part of the English language because it is a punctuation mark.
On the other hand, semicolon is used for specific identification especially when it involves a group, a very large one on a general basis. An example can be taken. A large number of the world's population is unemployed; very few are with jobs.