Explanation:

When an object is placed at 2F, it forms a real, inverted image of the same size.

Using, the lens' formula,

v

1

−

u

1

=

f

1

We know that magnification m=

u

v

=

h

O

h

I

Given that the size of image is same as that of the object, we have v=u

Also, since object is infront of the mirror u=−v, using sign convention

Substituting in the lens' formula, we have,

v

2

=

f

1

Hence, v=2f

Since u=−v. Hence, u=−2F, i.e. the object must be placed at position 2F in front of the convex lens.

So, option B is correct