Concept:The most beloved act of worship after the obligatory duties is bringing happiness to another Muslim.
Explanation:The five major pillars of Islam are the shahadah, salat, zakah, sawm, and hajj.
After performing these obligatory acts, the Prophet (SAW) was asked which good deed is best.
He taught that the best act of worship is to make a fellow Muslim happy.
This may be done by teaching beneficial knowledge, offering financial help, or showing kindness in daily dealing.
Such a deed reflects sincere faith and strengthens the bond of brotherhood in the Muslim community.
It ranks higher than optional acts such as performing nawāfil prayers or devoting time solely to dhikr.
This is because serving others brings direct relief to a believer and spreads love among the people.
Therefore, the option that mentions making a fellow Muslim happy is the correct choice.
Answer:C. make a fellow Muslim happy.