The Viceroy of India who followed an aggressive 'forward policy' towards Afghanistan, which led to the Second Anglo-Afghan War (1878-1880), was:

Lord Lytton (Robert Bulwer-Lytton), Viceroy of India from 1876 to 1880, followed an aggressive "forward policy" towards Afghanistan, which led to the Second Anglo-Afghan War (1878-1880).

Background:

• In the 19th century, Britain and Russia were rivals in Central Asia (the "Great Game"); the British feared that Russia might use Afghanistan to threaten India.
• Some earlier Viceroys had followed a policy of "masterly inactivity", avoiding interference in Afghanistan.

Lytton's forward policy:

• The Conservative government of Benjamin Disraeli in Britain wanted a firmer policy against Russia.
• Lytton demanded that the Amir of Afghanistan, Sher Ali, accept a British mission at Kabul.
• When Sher Ali received a Russian mission but refused a British one, Lytton declared war (November 1878).

The Second Anglo-Afghan War:

• British forces invaded Afghanistan; Sher Ali fled and died.
• His son Yakub Khan signed the Treaty of Gandamak (1879), which gave the British control over Afghan foreign policy and allowed a British Resident at Kabul.
• Soon after, the British Resident, Sir Louis Cavagnari, was killed in Kabul, and fighting resumed.
• The war was finally ended under the next Viceroy, when Abdur Rahman was recognised as Amir.

Other events of Lytton's time:

• The Great Famine of 1876-1878 in south and west India, in which millions died.
• The Delhi Durbar (1877), held with great pomp during the famine, was widely criticised.
• The Vernacular Press Act (1878), which restricted the Indian-language press.
• The Arms Act (1878), which required Indians to have a licence to keep arms.
• The maximum age for the Indian Civil Service examination was lowered from 21 to 19 (1876), making it harder for Indians.
• Cotton import duties were removed, which helped British manufacturers.

Why not the other options?

• ✗Mayo, Northbrook and Dufferin followed other policies.