Comprehensive and Detailed Explanation (150--250 words):

Two key clauses permit a lender to enforce foreclosure:

Acceleration clause -- allows the lender to declare the entire debt immediately due and payable if the borrower defaults. Without this clause, the lender could only sue for past-due installments.

Power of sale clause -- common in Massachusetts ''title theory'' mortgages, it authorizes the lender to sell the property at public auction without going through full judicial foreclosure.

The alienation clause (also called a ''due-on-sale'' clause) allows the lender to demand payoff when the property is transferred, not for foreclosure. The escalation clause allows interest rate or payment adjustments, not foreclosure.

Therefore, the correct pair that authorizes foreclosure is D: acceleration clause and power of sale clause.