Explanation:

Let’s break this down:

- The total number of red and blue balls in both the cylinder and square box is 180.

- We’re supposed to find the number of blue balls in the square box.

Statement I:

- There are 70 balls in the square box.

- But we don’t know how many are blue and how many are red.

- Alone, this isn’t enough.

Statement II:

- There are 30 blue balls in the cylinder.

- These 30 are half the number of red balls in the box—so the red balls in the box are 60.

- Alone, we still don’t know the number of blue balls in the square box.

Combine I and II:

- Square box: 70 balls in total.

- Box has 60 red balls (from II), leaving 10 balls which must be blue.

- So, both together give us a unique answer.

Look at the options:

1. Means you only need one statement (not true here).

2. Means either statement is enough (nope).

3. Means you need both statements together (yes, that’s right).

4. Means even both together aren’t enough (not the case).

So the correct answer is:

Option:3, 3