On the first day of a social media ad campaign, a website had 15 unique visitors. Over the following several days, the website received three times the number of unique visitors as the previous day. The number of visitors, v, can be modeled by v=15⋅3^(d−1), where d is the number of days in the campaign. On which day of the ad campaign did the website have 10,000 visitors?

A) 4
B) 7
C) 9
D) 6