Answer:
This question is asking to identify the variable in the experimental statement.
The eye chart is the CONTROL VARIABLE
Explanation:
An experiment consists of several variables to look out for in order to achieve any significant result. These variables are independent variables, dependent variables and control variables. Although independent and dependent variables are the major experimental variables, but control variables are also important.
A control variable is the variable that remains constant or unchanged throughout the experiment. Any change to the control variable will affect the dependent and independent variables. In this question, the eye chart is the CONTROL VARIABLE because it remains constant or unchanged. The same eye chart is used for the experiment.
N.B: The distance to the eye chart is the independent variable while the number of letters visible on the line is the dependent variable. Hence, changing the eye chart (control variable) will affect the distance and the number of letters visible.
<span>Melanin helps protect the skin against effects of the sun such as skin cancers and premature aging. In African American skin, melanin provides a sun protection factor (SPF) equivalent to 13.4 compared to 3.4 in white skin and thus the former have lower incidences of skin disorders associated with exposure to the sun.</span>
When the heated part of the mantle rises through the cooler part , this is an example of Convection.
Explanation:
because the pressure exerted by artery is more than that of vein due to its narrow lumen and thick walls...causing it difficult to clot.
It may be determination (not sure though)
