Which of the following is an effect of dinitrophenol on oxidative phosphorylation
Inhibition of ATP synthesis

Dinitrophenol is an uncoupler.
Uncouplers cause uncoupling of oxidation and phosphorylation, i.e. they allow electrons transport to proceed without ATP synthesis.
Inhibition of cytochrome b
Blockade of both electron transport and ATP synthesis
Inhibition of ATP synthesis with normal electron transport
Inhibition of electron transport but not ATP synthesis