Among the following, whose rule was described as ‘the perfect dictatorship'?

Institutional Revolutionary Party in Mexico

Founded in 1929, as National Revolutionary Party and later renamed the Institutional Revolutionary Party, the PRI (in Spanish), exercised power in Mexico for almost six decades. Over a period of time, Plutarco Elías Calles, the founder of PRI, was able to capture the organisation and thereby the government. Elections were held at regular intervals and it was the PRI that won every time. Other parties existed in name only so as to give the ruling party greater legitimacy. The electoral laws were operated in a manner so as to ensure that the PRI always won. Elections were often rigged and manipulated by the ruling party. Its rule was described as ‘the perfect dictatorship’.