An element is decaying according to the model given by y left parenthesis x right parenthesis space equals open parentheses 1 third close parentheses to the power of x space plus space 7 where x is measured in days and y(x) is measured in grams. explain the correct meaning of the 7 in this situation.

a. initially, seven grams of the element were present at x = days.

b. the element is decaying at a rate of 7 grams/day.

c. after 7 days, there is 1/3 of the element remaining in grams

d. as the days continue to increase, the amount of element left approaches 7 grams.