Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture? 

• The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic number down the group

• In both the alkali metals and the halogens the chemical reactivity decreases with increase in atomic number down the group

• Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens

• In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group