Figure a-2—use the information in this chart to answer question 2. 2. the chart shown in figure a-2 is used to select the correct viscosity of oil depending on the temperature of the atmosphere in which the engine will be used. recommendations are given for temperatures in both the english system of measurement (degrees fahrenheit or 0f) and the metric system (degrees celsius or 0c). note that 320f is the same as 00c. these oil viscosity recommendations are for a particular manufacturer's engine (not necessarily all engines). based on the information in the table, which of the following oils should be used in a lawn mower engine that's regularly operated in an outdoor temperature of between 10 degrees and 20 degrees celsius? a. 5w-30 or 10w-30 b. sae 30 c. synthetic 5w-20 or 5w-30 d. 5w-20 or 10w-40