Q.The statement "all contracts are agreements, but all agreements are not contracts" is best explained by the fact that:
(A) Every contract must be reduced to writing
(B) Every agreement must satisfy the conditions of enforceability by law (Section 10) before it becomes a contract
(C) Every agreement automatically becomes a contract once both parties sign it
(D) A contract need not be an agreement at all

A contract (Section 2(h)) is defined as an agreement enforceable by law — so a contract is simply the subset of agreements that also clears the Section 10 bar.

Work through each option against the rule stated above; an agreement graduates into a contract only when it is enforceable by law, which is exactly the Section 10 test.

Every contract IS an agreement (Section 2(h) defines a contract as 'an agreement enforceable by law'), but not every agreement clears the additional bar of legal enforceability that Section 10 sets — a purely social agreement, for instance, is never intended to be legally binding.

Option-by-option analysis:

• (A) Writing is not a general requirement for a valid contract in Indian law.
• (B) Correct — enforceability by law under Section 10's conditions is exactly what separates a mere agreement from a contract.
• (C) Signing alone does not make an agreement enforceable if it fails Section 10's other conditions (e.g. no lawful consideration, no capacity).
• (D) A contract must, by definition (Section 2(h)), be an agreement — this reverses the actual relationship.