Group 2 in the penodic table contains the elements beryllium (Be), magnesium (Mg) , calcium (Ca) , strontium (Sf) )barium (Ba)and radium (Ra) What characteristic do these elements share ?

They are all alkali earth metals.

Explanation:

Their valence shell each has 2 electrons. Also, they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure. They form alkaline solutions, hydroxides, when reacting with water and their oxides are found in the earth’s crust.

the answer is definitely c.