Mrs. gannon is having her class make a winter decorations using pine cones. if each decoration needs 11 pine cones and mrs. gannon ha 18 students in her class. how many pine cones does mrs. gannon need?

When you solve one of these types of word problems, using multiplication is the most efficient method. 
If each student makes one decoration, then we can use the expression 11*18 to solve the problem. Or you could add eighteen elevens together, either method works.
11*18 = 198.
Mrs. Gannon needs 198 pine cones.
Hope that helped you!

The correct answer is c