A pharmacist combines two liquid solutions: $\frac{4t+2}{10t}$ liters and $\frac{t-3}{10t}$ liters into one container. Write the simplified expression for the total volume and state any $t$-values that are not allowed.

• A. $\frac{5t-1}{10t}$, with no exclusions
• B. $\frac{5t-1}{10}$, with $t\ne 0$ and $t\ne \frac{1}{5}$
• C. $\frac{4t+1}{5t}$, with $t\ne 0$
• D. $\frac{5t-1}{10t}$, with $t\ne 0$

Answer: (D)