Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

I look at you, you look at me, I raise my right, you raise your left. What am I?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

I’m tall when I’m young, and I’m short when I’m old. What am I?

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

Can you find out who is the kidnapper in below Picture and why, Explain ?