In the context of Mathura school of Art, during which of the following periods were a number of sculptures of Brahmanical deities, such as Kartikeya, Vishnu and Kubera carved?

The correct answer is Kushana.

The Mathura school of art flourished and reached its zenith during the rule of the Kushana Empire (circa 1st century CE to 3rd century CE). While the school is highly celebrated for producing the earliest indigenous images of the Buddha, it was also a prolific center for carving Brahmanical and Jaina deities.

During the Kushana period, there was a significant development in Brahmanical iconography in Mathura. Sculptors began producing distinct iconographic forms for various Hindu deities. Key features of this development include:
- Kartikeya: Depicted as a warrior deity, often holding a spear (shakti) and accompanied by his mount, the peacock.
- Vishnu: Represented with his characteristic attributes like the mace (gada), discus (chakra), and sometimes in his multi-headed forms (such as Vaikuntha Chaturmurti).
- Kubera: The god of wealth was carved frequently, portrayed as a corpulent deity holding a wine cup or a money bag, signifying prosperity and abundance.

Thus, it was under the patronage and cultural synthesis of the Kushana period that these diverse Brahmanical sculptures were carved extensively.