As online access to Chretien de Troyes's book Perceval; Or, The Story of the Grail, translated by Ruth Harwood Cline, is limited, below are a few ideas to help get you started.
One thing we can learn is that both the pure white lance that bleeds drops of blood from its tip and the magnificent grail are carried past a bed upon which two men sit, as we see in the following passage:
Out of a room a squire came, clasping
a lance of purest white: while grasping
the center of the lance, the squire
walked through the hall between the fire and two men sitting on the bed. (lines 3191-95)
We also know that prior to entering the castle, Perceval met a crippled Fisher King when Perceval inquired of fisherman if there was a way to cross the stream. When there turned out to be no way across the stream, Perceval was invited by the Fisher King to stay the night at his castle. We particularly see the noble fisherman Perceval meets described as the crippled Fisher King in the book's introduction, written by the translator, Ruth Harwood Cline: "At an impassable river, the youth saw a crippled nobleman fishing and was entertained magnificently at his manor" ("Introduction," p. xi).
Based on the fact that we know the lance and grail are carried past the bed of a crippled king, we can deduce that the grail symbolizes physical vitality, meaning physical strength.
For your second question, "Which details indicate that Perceval's story is a quest story," you seem to have a typo as answer choices 2 and 4 are exactly the same. However, we know that the lance and grail symbolize physical vitality; we also know it's very important to the story that Perceval failed to ask exactly why the lance was bleeding and who was being served with the grail; we know that failing to ask those questions was so important that he later decided to fulfill what was deemed an impossible quest just to ask those questions. If we know all those things, then we know that the castle in which Perceval was supposed to have asked those questions contains some sort of mystery.
Therefore, it makes most sense to say that Perceval's story is a quest story because "an enchanted castle provides answers to a mystery."