In this question, we need to identify four parts of a flower based on their functions or descriptions provided:

1. X: The part which produces pollen grains.
2. Y: The part where the female gamete is formed.
3. Z: The female reproductive part where pollen grains germinate.
4. W: The part of the flower which attracts insects.

To determine the correct option, let's explore each statement and match them with the options provided:

1. X: Anther - The anther is part of the stamen, the male reproductive organ of a flower. It is responsible for producing pollen grains. Hence, "Anther" is the correct choice for X.
2. Y: Ovary - The ovary is part of the pistil which is the female reproductive organ of a flower. It contains ovules, where the female gamete forms. Thus, "Ovary" is correctly matched with Y.
3. Z: Stigma - The stigma is the part of the pistil where pollen grains land and germinate during pollination. Therefore, "Stigma" correctly identifies Z.
4. W: Petals - Petals are brightly colored parts of the flower that attract insects for pollination. Hence, "Petals" is correctly matched with W.

After analyzing all the statements, the correct option is: Anther, ovary, stigma, petals.