Section 4. No corporation which is a “private foundation” as defined in section 509 of said Code, shall

(a) engage in any act of “self-dealing” (as defined in section 4941(d) of said Code), which would give rise to any liability for the tax imposed by section 4941(a) of said Code;

(b) retain any “excess business holdings” (as defined in section 4943(c) of said Code), which would give rise to any liability for the tax imposed by section 4943(a) of said Code;

(c) make any investment which would jeopardize the carrying out of any of its exempt purposes, within the meaning of section 4944 of said Code, so as to give rise to any liability for the tax imposed by section 4944(a) of said Code; or

(d) make any “taxable expenditures” (as defined in section 4945(d) of said Code) which would give rise to any liability for the tax imposed by section 4945(a) of said Code.