Step 1: Note that the sheet is \emph{transparent}. When the bottom half is folded backward along line PQ, the coloured strips from the bottom half overlap with those on the top half.
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Step 2: Folding backward causes:
\begin{itemize}
\item Vertical alignment of corresponding strips about PQ,
\item Reversal of left–right order for the folded portion,
\item Superposition of colours where strips overlap.
\end{itemize}
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Step 3: Examine each And compare it with the expected overlap pattern formed after folding:
\begin{itemize}
\item A: Colour order and overlaps do not match the fold symmetry — invalid.
\item B: Correct relative positions and colour overlaps — valid.
\item C: Produces an arrangement inconsistent with the folding reflection — invalid.
\item Option D: Matches the mirrored and overlapped strip configuration — valid.
\end{itemize}
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Final Answer:
\[
\boxed{\text{B, D}}
\]
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