The correct answer is D. 0.1288.

Solution using continuous compounding:

Future value = Present Value × e^(R×T)

Where R is the continuously compounded rate of interest, and T is the time to maturity.

$`$91` = 80e^{R \times 1}$$e^R = \frac{91}{80}$$R = \ln\left(\frac{91}{80}\right) = 0.12883$$

Alternative calculation:

Holding period return = S_T / S_0 − 1 = $91 / $80 − 1 = 1.1375 − 1 = 13.75%

Continuous Return = ln(1 + i) = ln(1 + 13.75%) = 0.12883

Therefore, the continuously compounded return is approximately 0.1288 (or 12.88%).