Answer is (a) human adaptability.
Rationale for rejecting b,c,d options:
Humans do not have a high fecundity, they can give birth to 1-3 offspring on an average.
The skin tone variation is an adaptation that is based on the geography. The sunlight intensity affects it. It is a part of the ability of the humans to efficiently adapt to their surroundings.
The body variation in the form of physical features is also the result of the ability of the humans to adapt to their surroundings.
Answer:
a. Gram negative
Explanation:
Lipopolysacchirides are found in the outer membrane of gram negative bacterial cell wall exposed to surface and are endotoxins that protects them from harmful chemicals. They are composed of lipids and polysaccharides. Gram negative bacteria are pathogenic due to their cell wall.
You should move this question to Mathematics instead. Or at least physics.
All elements of a ecosystem work together, the sun provides sun light which plants use photosynthesis for food. Small animals eat the producers aka the plants. Then other animals eat those. And so on if a plant wasn't alive then the whole ecosystem will fail.