For a continuous slab of 3 m x 3.5 m size, the minimum overall depth of slab to satisfy vertical deflection limits is

Answer: Option B

The given slab dimensions are 3m x 3.5m. Since (3.5/3) < 2, it is classified as a two-dimensional slab.

Deflection criteria as per IS 456:2000:
- For a simply supported slab, the span/depth ratio = 35
- For a continuous slab, the span/depth ratio = 40

Since we always design the slab for the shorter span (3m):

Effective depth (d) = 3000 mm / 40 = 75 mm

Thus, the minimum overall depth of the slab should be 75 mm to satisfy vertical deflection limits.