The Union Cabinet in $2015$ approved a landmark Memorandum of Understanding ($\text{MoU}$) on cooperation between India and the United Kingdom in which of the following sectors?

The Union Cabinet, chaired by Prime Minister Narendra Modi, granted ex-post facto approval to an $\text{MoU}$ signed with the United Kingdom on bilateral cooperation in the Energy sector. The primary areas of cooperation included electricity market reforms, integration of renewable energy grids, and energy efficiency.