Which sentence is an effective conclusion for this paragraph?

swimming is not just for summertime fun; it is actually a great way to exercise. swimming is one of the few forms of exercise that does not put any stress on a person’s joints. this makes it one of the safest forms of exercise. swimming is also good for reducing stress and improving blood pressure, cholesterol, and heart function.

a)
swimming can also improve blood flow to the brain, which could make you smarter.

b)
another good summertime sport is golfing.

c)
swimming can not only be fun, but can provide many health benefits as well.

d)
swimming is a great way to cool off!