Answer:
D : 2.17%.
Explanation:
The 26% is an APR(Annual Percentage Rate). This is a quoted rate that  a credit card company charges . It is also known as the  nominal rate.
Since the question is asking for a monthly rate, use the 26% and convert it into monthly rate. We have 12 months in a year; meaning, we will divide the nominal rate by 12;
Monthly rate = APR / n
APR = 26% or 0.26 as a decimal
n = compounding periods = 12
therefore, Monthly rate = 26% /12 = 2.17%