That's definitely a marigold. Plant them in your garden, around anything that's edible, to ward off pesky insects. They're very easy to regrow from the abundant seeds they produce, underneath the flower.
All answers are correct. This is Marigold. Garlands made out of this flower are popular in India. It is mostly used during the month of October for a popular festival "Dussera". On Dussera, apart from regular worship, the Garlands are used for regular prayers and also vehicles, tools and objects which are important to them. For example if Indians played Baseball then on Dussera Indians would offer it to the Baseball and the Baseball Bat. It is a way of saying Thank You to all of them. Not to forget to certain deities are also worshiped with these flower due to its colour.