The establishment clause would prevent

a church from being built in a Jewish area
the mayor’s office from displaying a cross
a citizen from placing a religious scene in a business
the president from having a Christmas party at home

the mayor’s office from displaying a cross

Explanation:

there are different religion existing. government has placed some limitations to government support of religion and also a form of measure to draw a line between government and religion. the establishment clause was formed and backed up by law by preventing government from supporting any religion at all thereby separating the state and the church by the supreme court.

The Establishment Clause are set of laws backed up by the supreme court that prevent government from being involved in any thing concerning religion.The government are thereby not allowed to make any laws aiding any religion. the use of the cross by the major office will show that the office of the major is in support of christian religion and this can cause an uproar in the society because the government on the formation of the establishment clause are expected to be religion neutral and also separate its activities from religion.

i think it's b or c hope this