The drive threory of motivation is based on the principle that organisms have certain psycological or physiological needs (in this case, hunger). When those needs are not satisfied, a tension in the organism is produced, and with it a drive to seek the satisfaction of that need.
Because the substance the rat recieves is nonnutritive (it doesn't reduce the rat's hunger), we can clearly see that the rat isn't performing the response because of this drive, seeking for the satisfaction of its hunger, but is motivated by another feeling. Therefore, this observation is problematic for the drive theory of motivation.
Elevation can affect the amount of sunlight that plants receive, the amount of water that plants can absorb and the nutrients that are available in the soil. As a result, certain plants grow very well in high elevations, whereas others can only grow in middle or lower elevations.
