You can improve the environment by not allowing smoking
The could protect it by them reducing the throttle to "no wake" speed when they are close to a shore line. Or even protecting the horeline from erosion.
Answer : B. some of the police force
Among the choices above, it is the phrase in letter b wherein the pronoun "some" refers to a single noun which is " the police force". As you can see, the police force refers to a group of policemen making it a collective noun taking the singular form of the verb. The other objects of the pronoun "some" in the other options are all in plural form such as economy cars, native people, and the 6y foods.
Sunscreen helps in protecting your skin from sunburn, reduces the risk of getting skin cancer, and also reduces the signs of aging. Make sunscreen your friend!