A

Step 1: Understand the behavior of a series RL circuit regarding resistance (R), inductance (L), and how they interact with frequency and current.
Step 2: For (i) To increase current in a series RL circuit, we can apply Ohm's Law ($I = \frac{V}{R}$). To increase the current, we need to decrease the resistance (R). Thus, (i) matches with [A] decrease R.
Step 3: For (ii) To increase phase angle in a series RL circuit, the phase angle ($\phi$) is given by $\tan(\phi) = \frac{X_L}{R}$, where $X_L$ is the inductive reactance. Increasing R will increase the denominator and hence decrease the phase angle. Therefore, to increase the phase angle, we should decrease the value of R. However, according to the answer options, this is not directly presented.
Step 4: For (iii) To decrease the phase angle in a series RL circuit, we can decrease the inductive reactance by increasing the frequency ($f$). The inductive reactance is given by $X_L = 2\pi f L$. Thus, (iii) matches with [C] increase frequency.
Step 5: For (iv) To decrease the current in a series RL circuit, we can connect a capacitor (C) in series or increase the resistance (R). Among the options provided, (iv) matches with [D] connect C in series as it introduces reactance that can decrease the overall current in the circuit.

Therefore, the correct pairings are:
(i) [A], (ii) [B], (iii) [C], (iv) [D]. However, since only [A] is identified in your original question, we summarize it as follows.