The diagram below shows the positions of the shadow cast by a stick at four different times during a day. Which of the following match the shadow to the correct time?
9 a. m.-----12 noon-----2 p.m.-----5 p.m.
(a) R-----Q-----P-----S
(b) Q-----S-----P-----R
(c) S-----P-----Q-----R
(d) Q-----S-----R-----P