In each of the following problem, a square transparent sheet with a pattern is given. How the pattern would appear when the transparent sheet is folded at the dotted line.

Correct — C.
Rule: a vertical fold mirrors the moving half left to right, and the transparent sheet shows both halves together.

The options show the right half dotted, so it folds onto the left.
The arc flips to bulge left, from the apex on the fold down to the base's left corner.
The triangle's right side lands on its left side, and the base's right half on its left half.

Result: an arc, the straight side joining its ends, and a horizontal base reaching the fold → option (c).

Why the others are wrong

• (a)
  Figure (a) — Option (a) has the arc and its straight side, but the third line slants from the left point down to the fold. The base is horizontal, and a vertical fold keeps horizontal lines horizontal.
• (b)
  Figure (b) — Option (b) is the right shape upside down: its horizontal line runs along the top and the arc meets the fold at the bottom. A vertical fold swaps left and right only.
• (d)
  Figure (d) — Option (d) hangs the arc below its straight side, meeting the fold at the bottom, and slants its other line up to the fold. After the fold the arc meets the fold at the top, at the apex.

A transparent-sheet fold lays one half on the other. Every line on the moving half is reflected across the fold, and because the sheet is see-through, the lines already on the other half stay visible.

Points on the fold do not move. A vertical fold swaps left and right but never top and bottom, so the apex, sitting on the fold at the top, stays exactly where it was.

Key facts

• A fold about a vertical line reflects the moving half left to right and leaves top and bottom alone.
• Anything lying on the fold line stays where it is.
• On a transparent sheet the result shows the lines of both halves together.

Common traps

• Turning the pattern upside down, as option (b) does, when the fold only swaps left and right
• Dropping the horizontal base, whose left half never moves, so a horizontal line must reach the fold

No directly related past PYQ was found.