The upright pyramid of numbers is absent in
- Pond
- Grassland
- Lake
- Forest
Answer
(4) Forest
Solution
In grassland, pond and lake ecosystems the number of producers (grasses, phytoplankton) is very large, so the pyramid of numbers is upright.
As per NCERT, in a forest (tree) ecosystem a single large tree supports a very large number of small herbivores (insects, birds),
the pyramid of numbers there is not upright (it is inverted / spindle-shaped).
Answer: (4)