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Bidyut sinha
Here no need to apply veloy addition theorem of special theory of relativity. First of all, the main thing you have to know, that is : with respect to any reference frame light/photon Particle has velocity "C". So here with respect to electron frame of reference ,photon has velocity "C".So oppositely, according to Photon frame of reference, electron has velocity "(-)C". So answer is (b)-C