The correct answer is (c), Section 40.
Section 40 of the Transfer of Property Act, 1882 deals with transfer by ostensible owner. It states that a person who is in possession of property as the ostensible owner of another person, and who transfers the property to a third person, is deemed to have been authorized to do so by the other person, unless the third person knows that the transferor is not the real owner.
For example, if A is in possession of a property as the ostensible owner of B, and A transfers the property to C, C will be the owner of the property, even if B does not authorize the transfer. However, if C knows that A is not the real owner of the property, then C will not be the owner of the property.
The other options are incorrect because they do not deal with transfer by ostensible owner. Section 39 deals with transfer of property by a person who is not the owner. Section 41 deals with transfer of property by a person who is not competent to transfer the property. Section 42 deals with transfer of property by a person who is under a disability.