When a man running on a level ground increases his speed by 4ms^(-1), if his kinetic energy increase by 125% his initial velocity is

When a man running on a level ground increases his speed by 4ms^(-1),

1.	When a man running on a level ground increases his speed by 4ms^(-1), if his kinetic energy increase by 125% his initial velocity is
Answer» `4 ms^(-1)` `8 ms^(-1)` `2 ms^(-1)` `6 ms^(-1)` ANSWER :B