Correct Answer  Option 1 : 35
Explanation
For two way slab of shorter span (up to 3.5 m) with mild steel reinforcement, the span to overall depth ratios is given below may generally be assumed to satisfy vertical deflection limits for loading class up to 3 kN/m2
Type of Beam

span/depth ratio for
Mild Steel

span/depth ratio for
HYSD bars

Simply Supported

35

28

Continuous Slab

40

32

Note:
For slabs spanning in two directions, the shorter of the two spans should be used for calculating the span to effective depth ratio.
For high strength deformed bars of grade Fe 415, the value given in the column of mild steel should be multiplied by 0.8 (as mentioned in the third column for HYSD bars).