Given, square base OP=OR=3∴P(3,0,0),R=(0,3,0)Also, mid-point of OQ is T(23​,23​,0).Since, S is directly above the midpoint T of diagonal OQ and ST=3.i.e. S(23​,23​,3)Here, DR's of OQ(3,3,0) and DR's of OS(23​,23​,3).∴cosθ=9+9+0​49​+49​+9​29​+29​​=18​⋅227​​9​=3​1​∴ Option (a) is incorrect.Now, equation of the plane containing the △OQS is∣∣​x33/2​y33/2​z03​∣∣​=0⇒∣∣​x11​y11​z02​∣∣​=0⇒⇒​x(2−0)−y(2−0)+z(1−1)=02x−2y=0 or x−y=0​∴ Option (b) is correct.Now, length of the perpendicular from P(3,0,0) to the plane containing △OQS is 1+1​∣3−0∣​=2​3​∴ Option (c) is correct.