In one study subjects were randomly given either 500 or 1000 milligrams of vitamin C daily, and the number of colds they came down with during a winter season was noted. In a second study people responded to a questionnaire asking about the average number of hours they sleep per night and the number of colds they came down with during a winter season.

A. The first study was an experiment without a control group, while the second was an observational

Step-by-step explanation:

I think your question is missed of key information, allow me to add in and hope it will fit the original one.  

A. The first study was an experiment without a control group, while the second was an observational

study.

B. The first study was an observational study, while the second was a controlled experiment.

C. Both studies were controlled experiments.

D. Both studies were observational studies.

E. None of the above is a correct statement.

My

a. Yes, The first study was an experiment without a control group because it were randomly given either 500 or 1000 milligrams of vitamin C daily, we do not know who was given 500 or 1000.

and

The second was an observational  because we can observe about number of hours they sleep per night and the number of colds.

option c) graph of line going through 1, 4 and 3, 10

step-by-step explanation:

let y equal to margo's coin collection

let x equal to number of years

at the begining x=0, y=1 → point=(x,y)→point=(0,1)

she adds 3 coins per year, then y=1+3x

at x=1, y=1+3(1)=1+3→y=4→point=(x,y)→point=(1,4)

at x=3, y=1+3(3)=1+9→y=10→point=(x,y)→point=(3,10)

the graph of line going through (1, 4) and (3, 10), then the option c is the correct.