It is yo trabajo because currently the verb is in infinity form but to put it in first person form you cross out the last two letters and add an o. So trabajar becomes yo trabajo.
1. TU comes el huevo
2. USTED come la pizza, señor Núñez?
3.YO no comparte el queso para cenar
4. EL tomo te en el desayunó
Pedro ERA alto y guapo.
The answer is Era