Rabi crops are crops that are sown in winter and harvested in spring. They require cool weather for their growth and development. Various crops are grown during the rabi season, including vegetables, cereals, oilseeds, and pulses. Among the options given, "c) Bajra" is not a rabi crop.

Below is a detailed explanation of the rabi crops mentioned in the options:

Cabbage (a rabi crop):
- Cabbage is a leafy vegetable that belongs to the Brassicaceae family.
- It is a cool-season crop and is typically sown in the winter season.
- Cabbage requires a temperature range of 15-20 degrees Celsius for optimal growth.
- It is harvested in the spring season.

Cauliflower (a rabi crop):
- Cauliflower is a vegetable that belongs to the Brassicaceae family.
- It is a cool-season crop and is typically sown in the winter season.
- Cauliflower requires a temperature range of 10-20 degrees Celsius for optimal growth.
- It is harvested in the spring season.

Bajra (not a rabi crop):
- Bajra, also known as pearl millet, is a cereal crop that belongs to the Poaceae family.
- It is a warm-season crop and is typically sown in the summer season.
- Bajra requires a temperature range of 25-35 degrees Celsius for optimal growth.
- It is harvested in the summer or rainy season, making it a kharif crop.

Pea (a rabi crop):
- Pea is a legume crop that belongs to the Fabaceae family.
- It is a cool-season crop and is typically sown in the winter season.
- Pea requires a temperature range of 10-20 degrees Celsius for optimal growth.
- It is harvested in the spring season.

In conclusion, among the options given, "c) Bajra" is not a rabi crop. It is a warm-season crop that is sown in the summer season and harvested during the summer or rainy season. The other options, including cabbage, cauliflower, and pea, are all rabi crops that are sown in the winter season and harvested in the spring season.