A car travels along the line OX with a uniform acceleration. At times t, and t₂, its positions are x, and x, respectively. Then its acceleration is (assume that at t=0 the car is at O) [ ] 2(x₂-x₂₁) 1₁1₂ (1₂+1₁) a) 2(x₂-x₂) 44 (42-4) b) 2(x₂₁-X₁1₂) 471₂ (1₂-1₁) c) d) 2(x₂1₁-x₂) t₁t₂ (1₂+1₁)​