Correct Answer: automatically; blink

Solution : The correct choice is the first option .

In the context of the passage:

• The word for the first blank is automatically . Humans blink their eyes automatically, meaning it happens as a natural, involuntary response to various stimuli, like protecting the eyes or maintaining moisture.
• The word for the second blank is blink . Adults blink their eyes about 15 times per minute. This choice maintains consistency with the context and represents the regular, reflexive action of closing and opening the eyes.

Therefore, the complete paragraph is: "Humans blink their eyes automatically to flush away the stream of cleansing tears produced by the ducts present in the corners of our eyes. Adults blink their eyes about 15 times per minute."