Answer
(a) Measured.
(b) Exact.
(c) Exact.
(d) Measured.
Work Step by Step
(a) Usually, the mass of a person is measured in a scale.
(b) The number of tablets of medication is usually exact, since it does not use any measurement tool to find it (directly or indirectly).
(c) $1 \space L = 1000 \space mL$ is an arbitary statement, and it does not come from a measurement.
(d) The distance between two points in real life is always measured/estimated.
