They would collapse as the sun gives the producers energy to grow i.e plants through photosynthesis. Without plants most animals would die out unless humans could somehow create a food in labs without animals or plants for 6 billion people. Ultimately it would be the death of the human race and just about everything on Earth apart from some plants that live in the deep depths of the sea which have adapted to not having as much sunlight.
Tachyon is not a particle.
The correct option is D.
Significant figure refers to the number of digits that are used to report a measured quantity. The amount of a significant number in a measurement always equal to the number of digits that are known with some degree of confidence and the last number, which is usually an estimate. When carrying out calculations with significant figures measurements, one must be careful to report the number of significant figure to reflect the least precise measurement.