Correct Answer - Option 1 : 97.63 kPa

__Concept:__

Coulomb's equation,

τ = C + σ_{n} tan ϕ

Where,

τ = Shear strength of soil

C = Apparent cohesion

σn = Normal stress on the plane of rupture

ϕ = Angle of internal friction

__Calculation:__

Given,

C = 80 kPa, σn = 100 kPa, ϕ = 10°

τ = C + σn tan ϕ

τ = 80 + 100 tan 10°

**τ = 97.63 kPa. **