Sometimes the IRS chooses returns randomly to request verification of identity and sometimes there is something on the return that triggers the request. No matter why the IRS has required you to verify your identity, you need to follow their instructions in order to receive your refund. If you do not verify your identity you will not get your refund.
https://turbotax.intuit.com/tax-tips/security/tips-for-handling-identity-verification-requests-from-...
https://www.irs.gov/identity-theft-fraud-scams/identity-verification-for-irs-letter-recipients
