Mark the correct pair

Sometimes due to biotic/abiotic factor the climax remain in a particular seral stage (pre climax) without reaching climax. Do you agree with this statement. If yes give a suitable example.

Ecological succession is ______ and ______ change in species composition.

Natural reservoir of phosphorus is

Given below are four statements $(a-d)$ each with one or two blanks. Select the options which is correctly fill up the blanks into two statements.

$(a)$ Ecological succession is a...$(i)$... and fairly predictable changes in the ....$(ii)$... of a given area

$(b)$ Ecological succession, entire sequence of communities that successively change in given area are called ...$(i)$....

$(c)$ Primary succession occurs on...$(i)$...

$(d)$ Secondary succession is ...$(i)$... than primary succession

In desert grasslands, which type of animals are relatively more abundant