An engineer is investigating ways to improve gas mileage. his initial hypothesis is, "if we use higher octane gasoline, then the gas mileage will increase." what should his control group be? a) the type of car used in the testb) using higher octane gasolinec) the gas mileage of the test vehiclesd) some cars using regular octane gasoline

The correct option is D

Explanation:

In proposing the hypothesis, the objective is to demonstrate that increasing the octane rating of the gasoline will increase the mileage it performs. There are two types of groups when carrying out this type of study. The experimental group to which the change proposed by the hypothesis is applied. And the control group, which is the one with which the hypothesis is contrasted, in these the tested factor is not applied.

Have a nice day!

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.