We have a unit rate that we can calculate as:

We can express this rate in different ways:
The artist takes 5/8 hours to make a portrait.
The artist makes 8/5 portraits per hour (if we calculate the unit rate in inverse form)
Then, comparing these statements to the ones in the list, the ones that are true are:
Option f: "each portrait took 5/8 of an hour to draw", and
Option a: "the artist drew 8/5 portraits per hour"
Answer:
Option f: "each portrait took 5/8 of an hour to draw"
Option a: "the artist drew 8/5 portraits per hour"