[v] vs. [$\theta$]
This question requires identifying a pair of sounds that differ in exactly two specific ways concerning how they are produced (articulation). The key articulatory parameters are usually: Place of Articulation, Manner of Articulation, and Voicing.
Let's examine the articulatory parameters for each sound pair:
The sound pair [v] and [$\theta$] differs in two articulatory parameters: voicing (voiced vs. voiceless) and place of articulation (labiodental vs. dental).
Therefore, the correct option is the one containing the pair [v] vs. [$\theta$].
Match the numbered parts of the vocal tract (in the diagram given below) with the correct label from those given in the box and choose the appropriate option.

LABELS a. Labial cavity |
| क | ख | ग | घ | ङ |
| /k/ | /kʰ/ | /g/ | /gʰ/ | /ŋ/ |
| प | फ | ब | भ | म |
| /p/ | /pʰ/ | /b/ | /bʰ/ | /m/ |