How would the pattern given on the square transparent sheet marked ‘X’ look when the sheet is folded along the dotted line?

When we fold the sheet along the dotted line, the resulting figure will be the mirror image of the original figure, thus the triangle originally pointing to the left will now point to the right, hence last option is eliminated.

As there is only a circle inside the triangle, thus in the answer figure there will only be a circle along the horizontal line (which is already present on the left side of X), thus only possible answer is the first one.

=> Ans - (A)