Answer:
The correct answer is option A. "directional selection".
Explanation:
Directional selection is a type of natural selection at which traits with extreme characteristics are selected over traits with medium characteristics. In this case, a long-term climatic change resulted in all seeds that are the fountain of food for finch becoming hard. This will result in a directional selection on bill size in the finch population, where large-billed birds will be selected over small and medium-billed birds.
Cell wall.
Made of cellulose and acts as a stronger cell membrane in a plant cell
U can do it your self its a cross word for crying out loud
Answer: B) are excited by light that falls in the center of their receptive field.
Explanation:
There are two types of bipolar cells present in the retina which are differentiated on the way the centres of their receptive fields respond to light. The names of bipolar cells are ON-centre and OFF-centre.
If a light fall at the centre of the receptive field of a bipolar cell, it will experience an exciting effect on that cell, resulting in it being depolarized, it is an ON-center cell.
Hence, the correct option is B.