Ether is required as a solvent in the Grignard reaction because ethers can:
a. Dissolve the Grignard reagent better than most other solvents
b. Trap byproducts that reduce yield in the Grignard reaction
c. Form a stable complex with the Grignard reagent
d. Destabliize the Grignard reagent to make it more reactive
e. Prevent damaging explosions in the Grignard reaction