The federal government borrows from the capital markets to cover budget deficits, which occur when government spending exceeds its revenues. Borrowing is done through the issuance of fixed-income securities such as Treasury bills, bonds, and notes. This process enables the government to fund public services, programs, and infrastructure projects without immediately raising taxes.

A. To raise capital for streets, sewers, and waterworks: While such projects are funded by borrowing, they are typically under the purview of municipal or provincial governments rather than the federal government.

B. To support the capital markets: This is an indirect result but not the primary reason for borrowing.

D. To support the expansion of corporations: Corporate expansion is financed through private or corporate capital markets, not federal borrowing.