Answer:
a. 0.68 M NaCl solution
Step-by-step explanation:
The tonicity of a solution can either be hypotonic, hypertonic and isotonic. Hypertonic solution is a solution which possesses a higher concentration of solute in relation to another solution.
According to this question, a solution is said to contain 0.15 M NaCl solute. This means that a solution that will be hypertonic to this solution will have a much more concentration of solute, which based on the options provided is the 0.68 M NaCl solution.