What type of pest lives in the soil, feeds on grass roots, and causes the grass to turn yellow and then brown?

Mole crickets are the correct choice because these pests are known for their burrowing behavior in soil where they primarily feed on the roots of various grasses. Their feeding can severely impact the health of the grass, leading to symptoms such as yellowing and browning as the grass struggles to absorb nutrients and water.

In contrast, lace bugs are typically found on foliage where they suck sap from the leaves, causing stippling and discoloration without the same soil-based attachment. Leafminers are larvae that tunnel within leaves, creating distinctive patterns, but do not interact with grass roots directly. Thrips are small, slender insects that feed on plants by piercing and sucking juices from leaves and flowers, but they are not associated with root feeding or soil. Hence, mole crickets are specifically linked to the described symptoms affecting grass due to their root-feeding habits.