Answer
correct Answer is gravitation
Explanation
In 2005, collision of deep impact probe with the nucleus of comet tempel 1 was carried out. In this probe the length of Tempel 1's nucleus was about 5km long. In this probe it was revealed that the nucleus behave as a rubble pile which is held together by gravitation.
In this probe speed of Tempel 1 which is moving towards the nucleus was 10km/s. In this probe series of images was recorded and cloud of debris was analyzed,It was discovered that comet is made up of a primordial chunk of solar system material. It was observed that Tempel 1's has tiny grains of silicates, iron compounds, complex hydrocarbons, and clay and carbonates thought to require liquid water to form it was more appropriate for a cosmic souffle, as the nucleus is apparently porous and fluffy.
The criteria of the indicator species that does not meet is:
<u>Found at the base of any food chain.</u>
<u>Option: B</u>
<u>Explanation:</u>
As an early warning system for environmental problems, indicator species are chosen for their sensitivity to environmental conditions. If the selected indicator species decrease in numbers or any health factor, it symbolizes to see for detrimental effects such as soil impurity, pollution in water/air, habitat fragmentation or drastic variation in climates.
Apart from being sensitive to change, these species must also be representative of the other organisms in the ecosystem, easily observable and must be sampled, and they should react continuously to environmental changes. So from the above conditions, it is clear that species found in any base of food chain is not the criteria.
Answer:

Explanation:
Given that,
Lightning flashes one mile (1609 m) away from you.
We need to find the time it take the light to travel that distance. Let the time be t. We know that,
speed = distance/time

So, the required time is 