Which of the following representations shows the pyramid of numbers in a forest ecosystem ?

Which one of the following is now being commercially produced by biotechnological procedures ?

In genetic engineering, a DNA segment (gene) of interest,is transferred to the host cell through a vector. Consider the following four agents (A-D) in this regard and select the correct option about which one or more of these can be used as a vecotr / vectors –
(A) a bacterium
(B) plasmid
(C) plasmodium
(D) bacteriophage

An example of endomycorrhiza is -