Answer:
option c. 10.2%
Explanation:
Number of visitors to Alec's website in February = 1,544
Number of visitors to website in March = 1,386
Number of decreasing members = 1544 - 1386 = 158 visitors
decrease percentage =

=

= 10.233 ≈ 10.2%
percentage decrease of the number of visitors is 10.2%.
Option c. is the answer.