Final answer:
To find the percent increase, subtract the initial weight from the final weight, divide by the initial weight, and multiply by 100.
Step-by-step explanation:
To find the percent increase in the kitten's weight since the first visit, we need to calculate the difference in weight and divide it by the initial weight, then multiply by 100 to find the percentage.
The kitten's weight increased by a total of 12 ounces (on the second visit) and another 10 ounces (on the third visit).
Therefore, the total weight gain is 12 ounces + 10 ounces = 22 ounces.
The initial weight was 18 ounces, so the percent increase in weight is (22 / 18) * 100 = 122.22%.
Rounded to the nearest whole percent, the kitten's weight has increased by 122% since the first visit, so the correct answer is D) 156%.