Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: The police officers ascended the steps and checked every passport individually . I was again surprised when I did n't get my passport stamped . Once you cross one border within Central America , a stamp is not necessary until you leave the region .

Question: Why did the police check each passport ?
To check for criminals entering the country
To verify identities.