It seems like the answer is C, you really just need to use the process of elimination.
Total number of students (male and female) in the college=2760. Total number of students including both male and female represents 100% (percentage) of students which is equal to 2760 number.
Number of male students is 65% (percentage) which is equal to = 1794. So, total number of female students are (100-65)%=35% (percentage) which is equal to =966 numbers.
Alkali Metals (Group 1) elements experience an increase in the vigour of their reaction in water as they go down the group (as the atomic number increase). As such the most reactive Alkali Metal would be
FRANCIUM, which is at the base of Group One.
Quite frankly, you do not want Francium to react with water- that's a huge explosion on your hand.