Refer to figure.
The easiest way to answer these types of questions is to draw it out, as in the figure. The easiest way is to convert all the bearings in to a QDR (magnetic bearing FROM), as these can easily be drawn and the directions worked out.

Firstly you need to know where your aircraft is. The figure in the question gives you a DI with a heading of 225 and an RBI with a bearing of 065.

Heading + Relative Bearing = Bearing. 225 + 065 = 290. This is your QDM (magnetic bearing TO), but we need to find the QDR as this is where the aircraft is. 290 - 180 = QDR of 110. Draw the aircraft on a heading of 225° on this bearing, as in the figure.

You can then work through every option, drawing on the QDRs for each one, and working out the correct answer.

To intercept QDR 270°, continue on the present heading and turn left away from the NDB --> INCORRECT. If you turn left you will never intercept QDR 270 as you are turning away from it.

To intercept QDM 315°, continue on the present heading and turn right towards the NDB --> CORRECT. QDM 315 = QDR 135, so you will continue ahead and then turn right to fly towards the NDB.

To intercept QDM 270°, continue on the present heading and turn right towards the NDB --> INCORRECT. QDM 270 = QDR 090, which is behind you. Continuing and then turning right will never intercept a radial that is behind you.

To intercept QDR 180°, continue on the present heading and turn left towards the NDB --> INCORRECT. Whilst you will eventually intercept QDR 180, turning left will take you away from the NDB not towards it.