The correct answer is A. This is a contract of indemnity.
A contract of indemnity is a contract in which one party agrees to reimburse another party for any losses or damages that they may incur as a result of a particular event. In this case, A is agreeing to indemnify B against the consequences of any proceedings which C may take against B in respect of a certain sum of Rs. 500. This means that if C does take proceedings against B, A will be responsible for paying any damages that B is ordered to pay.
Option B is incorrect because it is a valid contract of indemnity. Option C is incorrect because it is not a contract of stipulation. Option D is incorrect because it is not one of the options listed.