Which of the below owl is odd one out?

What is the centre of gravity?

Which Number is the odd one out?

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

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?

Alpha is Beta's sister.

Gamma is a Beta mother.

Delta is Gamma's father.

Tango is Delta's mother.

Then,

How is Alpha related to Delta?

What Adam and Eve do not have but the rest of the people have?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

I have Rs.50 and I spend it in the way as below.

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?