Which of the following processes occurs at a faster rate?

Carnivores are

Climax stage is achieved quickly in secondary succession as compared to primary succession. Why?

$Mr. X$ is eating curd. What is his trophic level in the food chain for this food?

Which of the following statements regarding food chains are considered correct?
$(1)$ Removal of $80\%$ of tigers from an area results in greatly increased growth of vegetation.
$(2)$ Removal of most carnivores results in an increased population of deer.
$(3)$ The length of food chains is generally limited to $3-4$ trophic levels due to energy loss.
$(4)$ The length of food chains can vary from $2$ to $8$ trophic levels.

Identify $X$ from the figure: