(Mecca/Medina)
The fifth pillar of Islam is a pilgrimage to

The fifth pillar of Islam is a pilgrimage to​ Mecca

Explanation:

The five pillars of Islam are the five basic tenets by which the Islamic people function and live their lives in religious terms

These include their praying habits and general habits that would apply to all of their life and not just the time of their prayers.

The last and the rather most outlandish of this is Mecca which is their holy pilgrimage.

Whoever, it is allowed for some one who cannot go to Mecca to not go and do penances for the people that can go to Mecca.

So it is not absolute compulsion.

the berlin blockade was an international crisis that arose from an attempt by the soviet union, in 1948–49, to force the western allied powers (the united states, the united kingdom, and france) to abandon their post-world war ii jurisdictions in west berlin. in march 1948 the allied powers decided to unite their different occupation zones of germany into a single economic unit. in protest, the soviet representative withdrew from the allied control council. coincident with the introduction of a new deutsche mark in west berlin (as throughout west germany), which the soviets regarded as a violation of agreements with the allies, the soviet occupation forces in eastern germany began a blockade of all rail, road, and water communications between berlin and the west. on june 24 the soviets announced that the four-power administration of berlin had ceased and that the allies no longer had any rights there.

the answer would be c