Which of the following actions would likely raise homeowner's insurance premiums? building the home in the floodplain of a river installing a monitored alarm system living in a safe neighborhood with little crime choosing not to install a swimming pool

Insurance is a coverage that assesses the risk of a certain item/person. If that item/person is in good condition, your insurance will be lower because it's less likely it'll get damaged. 
This is why if you have a bad driving history, your car insurance is high (as there is a high risk). 
If you were to instal an alarm, live in a safe neighbourhood or choose not to install a swimming pool you would actually reduce your insurance.
If you have an alarm, you are less likely to have stuff stolen (safer = less risk).
Living in a safe neighbourhood is safer = less risk.
Not installing a pool means your property remains the same value (putting a pool could increase it), higher risk of someone drowning in the pool, or hurting themselves. So by not building the pool, you'll have a safer environment = less risk.

If you build your house in a floodplain, the chance of your house getting damages by a flood is very very high, so you will have to pay more as there is an increased risk.