Steam and velocity potential functions for a two-dimensional flow field given by u = -2x and v = 2y area) ψ = 2xy, ϕ = x2 – y2b) ψ = x2 – y2, ϕ = 2xyc) ψ = x2 y2, ϕ = x2 + y2d) ψ = x2 + y2, ϕ = x2y2

• A. a
• B. b
• C. c
• D. d