Which region was called the "nursery of the Bengal Army"?

Awadh

The correct answer is Option (3) → Awadh

"It is also important to remember that close links existed between the sepoys and the rural world of North India. The large majority of the sepoys of the Bengal Army were recruited from the villages of Awadh and eastern Uttar Pradesh. Many of them were Brahmins or from the “upper” castes. Awadh was, in fact, called the “nursery of the Bengal Army’’. The changes that the families of the sepoys saw around them and the threats they perceived were quickly transmitted to the sepoy lines. In turn, the fears of the sepoys about the new cartridge, their grievances about leave, their grouse about the increasing misbehaviour and racial abuse on the part of their white officers were communicated back to the villages. This link between the sepoys and the rural world had important implications in the course of the uprising. When the sepoys defied their superior officers and took up arms they were joined very swiftly by their brethren in the villages. Everywhere, peasants poured into towns and joined the soldiers and the ordinary people of the towns in collective acts of rebellion.".