The correct answer is option 2: All internal threats were to be handled by the ally alone, with no help from the British.

The Subsidiary Alliance was a policy introduced by Lord Wellesley, the Governor-General of India, in the early 19th century. It aimed to establish British control over various princely states in India. The alliance had several features, which are explained below:

1. Option 1: The British were responsible for protecting the ally from any external threats. This means that the British would defend the ally if it was attacked by an external enemy. This feature ensured the security of the princely states and made them dependent on the British for defense.

2. Option 2: All internal threats were to be handled by the ally alone, with no help from the British. This option is correct as it states that the princely states had to handle any internal rebellions or uprisings without direct assistance from the British. The British deliberately left this responsibility to the ally, as it weakened the internal power and stability of the states.

3. Option 3: The ally was to provide resources for maintaining a British armed contingent stationed in its territory. This means that the princely states were required to bear the cost and provide resources for