"the elders of that city shall take a heifer that has not been worked": and not the elders of Jerusalem. And Jerusalem does not bring an eglah arufah (the heifer of the broken neck).
"they shall take a heifer" ("eglath bakar"): R. Eliezer says: "eglath" — (up to) one year old; "parah" (a cow, the parah adumah [viz. Bamidbar 19:12]) — two years old. The sages say: "eglah" — (even one that is) two years old; "parah" — three or four years old — it being written (in respect to the former) "eglath bakar." How is this to be implemented? A two-year old satisfies both, "eglah" and "bakar."