Answer:
The correct answer is d. bottleneck effect
Explanation:
A bottleneck effect occurs when a large population of a species suddenly decreases in size due to some type of natural disaster like tsunami, earthquake, volcanic eruption, etc. This is a type of extreme genetic drift because in this many allele which was present in the old larger population might lost and the new population has less allele than previous population.
So here 98% of the population died in the earthquake and the remaining population has broader stripes on average than the initial population therefore here the squirrel population experienced bottleneck effect.
 
        
             
        
        
        
Answer: Matter and Energy 
Explanation:
The producers make food by the help of the process known as photosynthesis.This is the way by which the energy from the sun is transferred from sun to the plants.
Matter is made and transferred from one tropic level to another tropic level. The organic matter is transferred from the producers to the consumers.
The primary consumer converts energy from them to the secondary consumers.
So, the conclusion is that matter and energy is transferred from one tropic level to another tropic level.
 
        
             
        
        
        
The environment is studied at different levels & stages.
Biosphere: The biosphere is the zone in which life exists. It consists of the atmosphere& the hydrosphere alongwith the earth surface where living beings live. 
The biome is a community of plants and animals (flaura & fauna).
Community: A community is a group of people/living beings who live in a specific location. It is used to describe two or more populations of different species that exist at same place.
Population: A population is the multiple individuals or living organisms of a single species that live in an area. 
The populations are formed by lalrge number of groups of organisms.
Group of populations form communities. The group of all communities form a biome, which exist in the biosphere. 
The diagram shows: