A Belgian Astronomer and Cosmotologist who formulated the modern Big Bang theory, which states that the universe began in a cataclysmic explosion of a small, primeval “super-atom”
1. 100,000% A. I simply googled C12 and it's the most stable Isotope of Carbon...
2. A as well.. 99% sure.. and so far my 99% sure has been 100% correct so ... :p
According to the statement we can deduce that the resulting amplitude of the wave pulse is zero when there is a destructive interference of two pulses and the chain is straight. At this point the potential energy will be zero, therefore when applying the energy conservation theorem, the potential energy must be equal to the kinetic energy and be conserved. The potential energy will be totally transferred as kinetic energy and therefore that will be the only energy present in the string.
Thus, the option C is correct.