"...as old as..." or "...as young as..."

[renzheng04]

I am learning English as a foreign language.Sometimes I come over a problem that I myself can not decide what is right English.Thank for any help.

I have to join the following sentences using "as...as".

A is 16 years old. B is also 16 years old.

Answer 1: A is as young as B.
Answer 2: A is as old as B.

Which of them is correct ?

[Casiopea]

Is it a trick question?

My guess, "years old", so "as old as"?

But "young" also works. Consider:

A is 4' tall and B is also 4' tall.
A is as tall as B; A is as short as B.

[renzheng04]

Thank you,Casiopia.

Do you mind doing me a favour when I have problem ?

[Casiopea]

That's what we're here for.

See you next time.