Cual de estos verbos es irregular en el preterito?
querer
hablar
comer

The verb which is irregular in the preterite is querer.
When it comes to hablar and comer, they are both regular verbs. This means that in order to conjugate them, you just need to delete -ar for hablar and -er for comer, and add the following suffixes: é, aste, ó, amos, asteis, aron for hablar, and í, iste, ió, imos, isteis, ieron for comer.
However, when it comes to querer, you have to learn the entire conjugation by heart: quise, quisiste, quiso, quisimos, quisisteis, quisieron.