The public school employer shall grant a request for recognition filed pursuant to

Section 3544, unless any of the following apply: (

a) The public school employer doubts the appropriateness of a unit. (

b) Another employee organization either files with the public school employer a challenge to the appropriateness of the unit or submits a competing claim of representation within workdays of the posting of notice of the written request. The claim shall be evidenced by current dues deductions authorizations or other evidence such as notarized membership lists, or membership cards, or petitions signed by employees in the unit indicating their desire to be represented by the organization. The evidence shall be submitted to the board, and shall remain confidential and not be disclosed by the board.

The board shall obtain from the employer the information necessary for it to carry out its responsibilities pursuant to this

section and shall report to the employee organizations seeking recognition and to the public school employer as to the adequacy of the evidence. If the claim is evidenced by the support of at least percent of the members of an appropriate unit, a question of representation exists and the board shall conduct a representation election pursuant to

Section 3544.7, unless subdivision (

c) or (

d) of this

section applies. (

c) There is currently in effect a lawful written agreement negotiated by the public school employer and another employee organization covering any employees included in the unit described in the request for recognition, unless the request for recognition is filed less than days, but more than days, prior to the expiration date of the agreement. (

d) The public school employer has, within the previous months, lawfully recognized another employee organization as the exclusive representative of any employees included in the unit described in the request for recognition.