Question: Which of the 31 Mexican states is home to the mountain frog Ptychohyla zophodes?

Context paragraphs:
Banded stream frog: The banded stream frog, also known as the banded sand frog, Cape grass frog, Cape stream frog, long-toed frog, mountain frog or Jonkersberg frog (Strongylopus bonaespei) is a species of frog in the Pyxicephalidae family.  It is endemic to South Africa.

Alcalus baluensis: Alcalus baluensis is a species of frog in the family Ceratobatrachidae.  It is endemic to northern and western Borneo and found in Brunei, Indonesia, and Malaysia.  Its common name is Balu eastern frog or dwarf mountain frog.  It was placed in Dicroglossidae before being transferred to Ceratobatrachidae in 2015.

Quasipaa fasciculispina: Quasipaa fasciculispina is a species of frog in the Dicroglossidae family.  It is known under many common names: spiny-breasted giant frog, spiny-breasted frog, spine-glanded mountain frog, and Thai paa frog.  It is found in the Cardamom Mountains in southwestern Cambodia and southeastern Thailand.

Ptychohyla zophodes: Ptychohyla zophodes is a species of frog in the family Hylidae endemic to the Atlantic slopes of northern Oaxaca, Mexico.  Before being described as a new species in 2000, it was mixed with "Ptychohyla leonhardschultzei".

Mountain frog: The mountain frog or red and yellow mountain frog ("Philoria kundagungan") is a species of frog in the family Myobatrachidae.

List of national parks of Mexico: Mexico recognizes 67 federally protected natural areas as national parks (Spanish: "Parques Nacionales" ), which are administered by the National Commission of Protected Natural Areas (CONANP), a branch of the federal Secretariat of the Environment and Natural Resources.  Together, they cover a combined area of 1,432,024 ha in 23 of the 31 Mexican states and the independent district of Mexico City, representing 0.73% of the territory of Mexico.

Loveridge's frog: The Loveridge's frog ("Philoria loveridgei"), also known as the masked mountain frog, is a species of frog in the family Myobatrachidae.

Oaxaca: Oaxaca ( , ] , from Nahuatl: "Huāxyacac" , ] ), officially the Free and Sovereign State of Oaxaca (Spanish: "Estado Libre y Soberano de Oaxaca" ), is one of the 31 states which, along with the Federal District, make up the 32 federative entities of Mexico.  It is divided into 570 municipalities, of which 418 (almost three quarters) are governed by the system of Usos y costumbres (customs and traditions) with recognized local forms of self-governance.  Its capital city is Oaxaca de Juárez.

Chrysopaa sternosignata: Chrysopaa sternosignata is the only species in the monotypic genus Chrysopaa of the Dicroglossidae family.  It is found in Balochistan, Pakistan, Kashmir (Pakistan and India) and in Afghanistan.  Its common names include Baluch Mountain frog, karez frog, Malir paa frog, and Murray's frog.

Nothophryne broadleyi: Nothophryne broadleyi (common name: Broadley's mountain frog, mongrel frog) is a species of frog in the Pyxicephalidae family found on Mount Mulanje (Malawi) and Mount Ribaue (Mozambique).  It is monotypic within the genus Nothophryne.

Supporting paragraphs: Ptychohyla zophodes Oaxaca
Answer: Oaxaca