Answer:
The correct answer is - 47 days approximately.
Step-by-step explanation:
In this given graph is the decay graph of mercury-203, there is a representation of the relation of change in the amount of the mercury -203 with the time in days. The red arch is showing the change of parent isotope percent with elapsed time and the green dashed arch showing the daughter isotope percentage with isotope.
The half-life is the required time to decay an element to half of its inital amount, according to the definition the half-life of parent isotope mercury-203 is the amount where the red arch is present at 50% in the graph that is 47 days approximately.