Study the given flow chart.
What can P, Q, R and S be?
AP-Spectacle lens, Q-Ceramic tile, R-Iron rod, S-Window pane
BP-Steel jug, Q-Rubber band, R-Mirror, S-Window pane
CP-Iron ball, Q-Metal Spring, R-Window pane, S-Spectacle lens
DP-Ceramic tile, Q-Window pane, R-Rubber band, S-Iron rod