The correct answer is option 2, which states that the `Bombay Plan` drafted by GD Birla and J.R.D. Tata emphasized public sector investment in infrastructure and heavy industries.

Option 1 suggests that the plan advocated for the private sector to invest in heavy industries, implying that the government should leave the economy entirely to private investments in sectors like heavy industries.

Option 3 states that the plan focused on annual planning, which is not mentioned in the original question.

Option 4 proposes that the plan emphasized the private sector bearing the financial burden of investments in the industrial sector, particularly in areas with low returns. However, this option does not align with the emphasis on public sector investment in the original question.

Therefore, option 2 is the most accurate representation of the key emphasis of the `Bombay Plan.` It highlights the need for the government to invest in infrastructure and heavy industries.