Step 1: Recall what quorum means.
Quorum is the minimum attendance needed before a House can validly conduct business.
Step 2: Recall the constitutional fraction fixed for Parliament.
Article 100 fixes this quorum at one-tenth of the total membership of either House.
Step 3: Eliminate the other fractions.
Two-thirds and similar higher fractions apply to matters like amendment majorities, not the basic quorum requirement.
\[ \boxed{\text{One-Tenth}} \]