Correct Option
Assertion (A) states that Muhammad Bin Tughlaq left Delhi and resided in a camp called Swarga-Dwari for two years. This is historically accurate. During his reign (1325-1351 CE), the Sultan did temporarily relocate to a camp near Kanauj, known as Swarga-Dwari, for approximately two years.
Reason (R) states that Delhi was ravaged by plague and many people died at that time. This is also factually correct. Contemporary accounts, including those of Ibn Battuta and Ziauddin Barani, confirm that Delhi suffered from severe epidemics, likely plague, alongside famine, leading to widespread death and devastation during this period.
The severe conditions in Delhi, particularly the widespread disease and mortality, directly compelled Sultan Muhammad Bin Tughlaq to abandon the city temporarily and move to Swarga-Dwari. Therefore, Reason (R) is the correct explanation for Assertion (A).
Incorrect Options
Options 2, 3, and 4 are incorrect because both Assertion (A) and Reason (R) are individually true, and Reason (R) accurately explains the cause for Assertion (A).