Questions

Glaucoma is usually caused by high pressure on the optic nerve which leads the loss of eye sight.

The chief capacity of vitamin K is to help our blood clot so that we don't bleed too much.

Vitamin K is actually made up of two different types of vitamins, Vitamin K1 and Vitamin K2. They are both responsible for helping the blood to clot so that people do not bleed to death. Vitamin K1 can be consumed by eating leafy green vegetables, such as kale and spinach, as well as other vegetables, such as broccoli and collard greens. Meats, cheeses, and eggs can provide a great source of Vitamin K2.

Body cells that respond to insulin include liver cells and many other cells in the human body.

The given sentence is in simple present tense and states a general fact, hence the latter half of the sentence with the blank will also be in the simple present tense. Since the subject in the latter part of the sentence is singular .i.e. 'the number', the verb will be followed accordingly. Hence, option 4 is the correct answer.