Final answer:
To determine a change in blink, measuring blink frequency is the most effective and direct method, providing a clear and quantifiable measure of the rate at which blinking occurs.
Step-by-step explanation:
The most effective way to determine if a change in blink has occurred would be C. Measuring blink frequency. When assessing changes in blinking, we are primarily interested in how often the blinks occur over a certain time period. Blink frequency can be a marker of several neurological and physiological conditions and measuring it provides quantitative data.
While analyzing eye movement patterns and assessing eyelid muscle activity can provide relevant information about eye function overall, they are less direct methods to measure blink changes specifically. Eye movement patterns can indicate conjugate movements and muscle function, but they do not measure blink rate. Assessing muscle activity via electromyography (EMG) can also inform about the health and activity of muscles controlling the eyelids, yet it is more invasive and not solely focused on blink rate.
Option B, Asking if new matter was formed, is not relevant to the question at hand as it pertains to a concept in chemistry, whereas we are discussing a biological function.