Which element is likely to react violently with water? a) carbon
b) beryllium
c) cesium
d) sulfur

I think the answer is beryllium.

because it's not sulfur or carbon and probably not cesium

10 years is the answer

a basic emergency supply kit could include the following recommended items: water - one gallon of water per person per day for at least three days, for drinking and sanitation. food - at least a three-day supply of non-perishable food. battery-powered or hand crank radio and a noaa weather radio with tone alert.