A

Step 1: In a series AC circuit comprising a resistor (R), inductor (L), and capacitor (C), the phase angle ($\phi$) between the electromotive force (e.m.f.) and the current can be determined using the following relationship based on the impedance of the circuit.
Step 2: The impedance (Z) of a series LCR circuit is given by:
$$ Z = \sqrt{R^2 + (X_L - X_C)^2} $$
where $X_L = \omega L$ is the inductive reactance and $X_C = \frac{1}{\omega C}$ is the capacitive reactance.
Step 3: The phase angle $\phi$ (angle between the e.m.f. and current) is determined by the tangent of the angle:
$$ \tan(\phi) = \frac{X_L - X_C}{R} $$
Step 4: The phase angle can range from $0$ (when the circuit is purely resistive) to $\frac{\pi}{2}$ (when the circuit is purely reactive).
Conclusion: Therefore, the phase angle between the e.m.f. and current in a series AC circuit is from $0$ to $\frac{\pi}{2}$. Thus, the correct answer is Option A.