Which of the following needs a proof?

State whether the following statement is True or False. Justify your answer.
"For every line $l$ and for every point $P$ not lying on a given line $l$,there exists a unique line $m$ passing through $P$ and parallel to $l$." This is known as Playfair's axiom.

Solve the following question using an appropriate Euclid's axiom:
In the figure,$X$ and $Y$ are the mid-points of $AC$ and $BC$ respectively,and $AX = CY$. Show that $AC = BC$.

The Greeks emphasized on:

In ancient India,the shapes of altars used for household rituals were:

The edges of a surface are ............