The rise of water in the dropper when the bulb is released is due to atmospheric pressure.
When you press the bulb, you increase the pressure inside the dropper. As a result, the air inside the dropper is expelled, creating a low-pressure zone. When you release the bulb, the atmospheric pressure pushes the water into the dropper to equalize the pressure, causing the water to rise in the dropper. This phenomenon is based on the principle of atmospheric pressure.
Therefore, the correct option is (D): atmospheric pressure.
Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.