Find the sources of biases in my SHORT survey!!!!!!!!!!!?

-Our high school has a maximum of 800 students in total





-I surveyed 200 people in my high school





-This came up to: 40 random students from each grade (grade: 7, 8, 9, 10 11) (40 x 5=200)





-I randomly asked students in our school cafeteria to do my surveys





THIS WAS MY SURVEY:





Which of the following COLD beverages do you drink the most?





a) Water


b) Juice


c) Soda


d) Milk


e) Energy Drink


f) Other





Which of the following HOT beverages do you drink the most?





a) Coffee


b) Tea


c) Hot Chocolate


d) Other





WERE THERE ANY SOURCES OF BIASES INVOLVED IN MY SURVEY? Please give me AS MANY as you can find!

Find the sources of biases in my SHORT survey!!!!!!!!!!!?
No. Well maybe if one grade is really big/small compared to the others.