Trimerous flower:
A trimerous flower refers to a flower that has its floral parts in multiples of three. The term "trimerous" comes from the Greek words "tri" meaning three and "merous" meaning parts. In a trimerous flower, the floral organs such as sepals, petals, stamens, and carpels are arranged in whorls of three.

Superior ovary:
A superior ovary is a type of ovary position in a flower. In a flower with a superior ovary, the ovary is located above the attachment point of other floral parts such as sepals, petals, and stamens. The term "superior" indicates that the ovary is positioned above the attachment point. This is in contrast to an inferior ovary, where the ovary is located below the attachment point of other floral parts.

Axile placentation:
Axile placentation refers to the arrangement of ovules within an ovary. In this type of placentation, the ovules are attached to the central axis or placenta of the ovary. The central axis is usually formed by the fusion of two or more carpels. The ovules are attached to the placenta along the central axis, and each ovule has its own stalk or funicle. Axile placentation can be seen in flowers with superior ovaries.

Explanation:
The characteristics mentioned in the question - trimerous flower, superior ovary, and axile placentation - are all characteristic features of the family Liliaceae. The Liliaceae family is a large family of flowering plants that includes many well-known species such as lilies, tulips, and onions. These characteristics can help in the identification and classification of plants belonging to the Liliaceae family.

In Liliaceae flowers, the floral parts such as sepals, petals, stamens, and carpels are arranged in multiples of three, indicating a trimerous flower. The ovary is positioned above the attachment point of other floral parts, indicating a superior ovary. Additionally, the ovules are attached to the central axis or placenta of the ovary, indicating axile placentation.

It is important to note that the other options - Solanaceae, Cucurbitaceae, and Compositae - do not exhibit all three characteristics mentioned in the question. Therefore, the correct answer is option A, Liliaceae.