What do art historians mean by the use of "hidden symbols" in the mérode altarpiece (fig. 19-10, fig. 19-11)?

Look at this painting by leonardo da vinci. this painting demonstrates da vinci's use of which of these to enhance the emotion of a painting

In areas where even the experts disagree; everyone has a right to his own opinion. i mean if answers aren’t given just like in lots of things; then it has to be just anyone’s opinion. is this dualism multiplicity relativism or commitment

The caves at lascaux were closed in 1963 because a. vandals were destroying the paintings b. the collective breath of the many visitors caused the paintings to corrode c. the weather was destroying the paintings d. the government of france wanted scholars to be able to study the work without distraction