Final answer:
As the third Guru of Sikhism, Amar Das reinforced the concepts of equality and community within the faith, institutionalizing practices like Langar and the Anand Karaj marriage ceremony.
Step-by-step explanation:
The contribution made by Amar Das to the development of Sikhism is noteworthy. As the third Sikh Guru, Amar Das further established the Sikh faith and formalized important practices.
He made significant efforts to reinforce the concept of equality among all, regardless of caste, which Sikhism strongly upholds.
His efforts also involved instituting Langar, a communal kitchen where everyone, irrespective of their social status, could eat together, emphasizing the Sikh values of hospitality and community.
Additionally, Guru Amar Das helped in setting up the Anand Karaj, the Sikh marriage ceremony, which is one of the cornerstones of Sikh rites and traditions.
The third Guru's contributions are essential in understanding how Sikhism evolved after Guru Nanak's foundation and how it dealt with social issues of that time, like the caste system, which it fervently opposed.