<u>Answer:</u> The Henry's law constant for oxygen gas in water is 
<u>Explanation:</u>
To calculate the molar solubility, we use the equation given by Henry's law, which is:

where,
= Henry's constant = ?
= solubility of oxygen gas = 
= partial pressure of oxygen gas = 2.1 atm
Putting values in above equation, we get:

Hence, the Henry's law constant for oxygen gas in water is 
Answer is: C. nuclear fission.
Nuclear fission is a nuclear reaction or a radioactive decay where nucleus of atom split into smaller ligher nuclei.
Nuclear fission is exothermic reaction which release large amounts of energy (electromagnetic radiation or as kinetic energy, which heat reactors where fission reaction take place).
The lower case letter represents the recessive allele.