The correct option is B False
Pyramid of numbers is not always upright. It can be both inverted as in an ecosystem where there are only large trees. Here, the producers are large trees, a single tree can support thousands of herbivores in the form of birds and also insects, caterpillars, flies, etc. So, actually, the producer is the least in number. The pyramid, therefore, will turn out to be inverted.
The pyramid of numbers can also be spindle-shaped. Like in a forest ecosystem, the producers are large size trees which make the base of Pyramid. The herbivores such as fruit-eating birds, deer, elephants etc. that make the primary consumers are great in number. And these herbivores support a fewer number of carnivores. Hence, the pyramid of numbers becomes spindle-shaped.