Step 1: Understanding the Question:
We have four statements about the Other Backward Classes (OBC). We must find which statements are true and then choose the option that lists exactly those.
Step 2: Check statement A:
OBCs are not one single block. They include many castes with different occupations, customs and levels of wealth, and their position changes from state to state. So A is TRUE.
Step 3: Check statement B:
The OBCs are mostly the middle and artisan castes of the caste order, such as cultivating and service castes. Untouchable castes are a separate group, now covered as Scheduled Castes. So B is FALSE.
Step 4: Check statement C:
Two national commissions looked at the backward classes before 1990. The first was the Kalelkar Commission in the 1950s and the second was the Mandal Commission in the late 1970s. So C is TRUE.
Step 5: Check statement D:
The backward class movements began early in the South, for example in Tamil Nadu and Karnataka, and reservations came there much before the North. So D is TRUE.
Step 6: Choose the option:
The true statements are A, C and D. This is option 2. Option 1 and option 3 include B, and option 4 also includes B, so they are wrong.
Final Answer:
Statements A, C and D are correct, so the answer is option 2.
\[ \boxed{2} \]