jarāmaraṇaṃ singular from maraṇa neuter
jati singular from jāti feminine
bhavo singular from bhava masculine
upādānaṃ singular from upādāna neuter
taṇhā singular from taṇhā feminine
vedanā singular from vedanā feminine
phasso singular from phassa masculine
saḷāyatanaṃ singular from saḷāyatana neuter
nāmarūpaṃ singular from nāmarūpa neuter
viññāṇaṃ singular from viññāṇa neuter
saṅkhārā plural from saṅkhāra masculine
avijjā singular from avijjā feminine
The above seems to correlate with every translation I have read. Note: saḷāyatanaṃ may appear to be translated as plural but it appears singular because it includes 'six'.
For example, all translations say: "What is feeling [singular]?" rather than "What are feelings [plural]?"
And what is feeling? Katamā ca, bhikkhave, vedanā? There are these six classes of feeling. Chayime, bhikkhave, vedanākāyā— Feeling born of contact through the eye, ear, nose, tongue, body, and mind. cakkhusamphassajā vedanā, sotasamphassajā vedanā, ghānasamphassajā vedanā, jivhāsamphassajā vedanā, kāyasamphassajā vedanā, manosamphassajā vedanā. This is called feeling. Ayaṃ vuccati, bhikkhave, vedanā.
The saṅkhārā condition is described as follows:
And what are saṅkhārā [plural]? Katame ca, bhikkhave, saṅkhārā?
There are three kinds of saṅkhārā. Tayome, bhikkhave, saṅkhārā— body saṅkhāro [singular], speech saṅkhāro [singular] and mind saṅkhāro [singular] kāyasaṅkhāro, vacīsaṅkhāro, cittasaṅkhāro.
Why is the Pali word 'saṅkhārā' in Dependent Origination plural where all other words are singular?