Section 20170 Of Article 4. Cities From California Public Contract Code >> Division 2. >> Part 3. >> Chapter 1. >> Article 4.

. All bids shall be presented under sealed cover and accompanied by one of the following forms of bidder's security:
  (a) Cash.
  (b) Cashier's check made payable to the city.
  (c) A certified check made payable to the city.
  (d) A bidder's bond executed by an admitted surety insurer, made payable to the city.