Concept:Identify the act of worship associated with the month of Ramadan in the same way that Hajj is associated with Dhul-Hijjah.
Explanation:Hajj is the primary act of worship performed in the month of Dhul-Hijjah.
By analogy, Ramadan is best known as the month in which Muslims are commanded to fast.
Since Sawm (fasting) is not among the options, pick the act that is most especially linked to Ramadan.
Sa'y is part of Hajj and Umrah, so it belongs with Dhul-Hijjah, not with Ramadan.
Iddah is a waiting period for a woman after divorce or the death of her husband.
Da'wah means inviting people to Islam and is not tied to any particular month.
I'tikaf is a devoted seclusion in the mosque that Muslims commonly observe during the last ten days of Ramadan.
Thus, Dhul-Hijjah is to Hajj as Ramadan is to I'tikaf.
Answer:B. I'tikaf