Answer: Option C
$$\eqalign{
& {\text{According to the question,}} \cr
& {\text{Amount = Rs}}{\text{. 3144}} \cr
& {\text{Rate = 8}}\% \cr
& {\text{Let, Principal = Rs}}{\text{. }}x \cr
& \therefore {\text{Time = }} \cr
& \frac{{30 + 29 + 31 + 30 + 31 + 30 + 31 + 7}}{{366}} \cr
& = \frac{{219}}{{366}} \cr
& \therefore {\text{SI = }}\frac{{{\text{P}} \times {\text{R}} \times {\text{T}}}}{{100}} \cr
& \Rightarrow 3144 - x = \frac{{x \times 8 \times 219}}{{100 \times 366}} \cr
& = {\text{Rs}}{\text{. 3000}} \cr
& \cr
& {\bf{Alternate}} \cr
& \Rightarrow {\text{P}} + \frac{{{\text{P}} \times 8 \times \frac{{219}}{{365}}}}{{100}} = 3144 \cr
& \Rightarrow {\text{P}} + \frac{{{\text{P}} \times 8 \times \frac{3}{5}}}{{100}} = 3144 \cr
& \Rightarrow 100{\text{P}} + \frac{{24{\text{P}}}}{5} = 314400 \cr
& \Rightarrow \frac{{524{\text{P}}}}{5} = 314400 \cr
& \Rightarrow {\text{P = }}\frac{{314400 \times 5}}{{524}} \cr
& \Rightarrow {\text{P}} = {\text{600}} \times {\text{5}} \cr
& \Rightarrow {\text{P = Rs}}{\text{.}} \, 3000 \cr} $$